I'll do this in descending order from the classes that i care the most about to the classes i care the least about
Mage: More unconditional AoE, i said this when Yogg was played in every competititve deck regardlesss of class back in 2016 and i'll keep saying it, whenever a class feels the NEED to use yogg-like cards it's because the class doesn't have enough defensive tools that are good, nor decent AoE, and no, flamestrike doesn't cut it, it may have been good in Arena but it's always been a mediocre card in constructed that you run because there's nothing better.
Rogue: reprint/retrain Vilespine Slayer, or have more class specific tutors for rogue cards, wit Galakrond nerfed rogue has to go back to a pure tempo deck, and since blizzard, wants rogue's class identity to be weak to wide boards and not have access to AoE but it hardly has anything worth mentioning when it comes to giant slayers now that Walk the Plank and vilespine are out of standard
Priest: I'm satisfied with Priest atm, can't really think about something other than stronger mid-range minions, i've always wanted a Mad Scientist like priest card that could play Shadowform i from your deck instead of secrets, but Blizzard doesn't like shadowform and they dont like cards mentioning other specific cards, mmaybe a 2 mana deathrattle that casts a 3 cost spell from your deck when it dies?
Hunter; i'm in a love/hate relationship with hunter, WIld hunter has probably the most interesting decks in the game imho, Even hunter, Deathrattle hunter either the Big beast or egg Variant, Secret hunter, all variants of spell hunter, Malygos hunter, Unseal the Vault hunter, and the wacky Otk decks you can pull off with Knuckles+Goblin Prank and/or Leorokk, heck i've otked with Gahz'rilla because there are enough cards that allow players to pull it off now, Sadly those decks are more of a happy coincidence created by player experimentation since for standard Blizzard doesn't really see hunter as a class that should do something other than go face with beasts so it keeps getting some weird aggressive beast support.
Warlock: Nothing, warlock may not be competitive in standard right now outside of quest malylock, but the thing is that Blizzard has learned how to deal with its hero power , Blizzard now knows how to print amazing synergestic warlock cards that aren't good on their own but have high sinergy potential in order to work alongside the heropower but not get broken by it, Plot twist and SUpreme archaelogy are amazing examples, they were mocked off because on paper theya re weak, but they are staples of any warlock combo deck either win wild or standard, while Kel'idan the breaker does everything warlocks like to do and with and added Bonus if you dra wit, Unstable felbolt is this card that's amazing as long as you aren't using it in a Zoo deck, so it doesn't really get broken by the hero power, then there's the discolock support, dark portal, the prime and enhanced dreadlord, all of them with their uses. In other words Blizzard has learned that the way of warlock is the way of lateral powercreep, so for warlock please keep doing a good job Blizz!
Paladin: the thig with Pala is that the current Blizzard team seem to be avid fans of DND and want their Paladin to feel Paladin/Cleric concept of DND, where instead of Paladins that are pure light and lawful good, you have tons of different archetypes with different domains that different paladins champion, paladin of conquest, Paladin of vengeance, Paladin of redemption, Paladin of the crown, Paladin of plants(no, seriously, this exists*), Paladin of vindictive holy radiant damage and finally the Oathbreaker Paladin which i'm pretty sure that's where Blizzard took its inspiration for making mummies since the oathbreaker paladin is a champion of undead, Blizzard wants paladins to champion different stuff and that's why we have gotten a paladin of murlocs and a Paladin of mechs and the s, which have had their time in the spotlight as well as the silverhand paladin , but the Paladin that champions dragons and the oathbreaker that champions undead have never had their time in the spotlight So yeah good dragon support and reborn minions for paladins, and hero cards that bolster or enhance the tribe that you are currenlty supporting because since it is a Paladin and it's championing something it would make sense if the Paladin class had wider access to hero cards than any other class, in fact doctor boom mad genius should probably have been a Paladin hero instead of a warrior hero
Warrior:For the love of god give Warrior some sort of high mana or build/up finisher for control, Warrior already has a lot of good control tools, but the crux of the matter is that we are basically forec to play aggressive warrior decks and no one plays control Warrior because it doesn't get finishers, yes you still have access to the old Alex one turn gromm the following turn with a 3 attack weapon equiped, but this no longer cuts it, stop giving it the, "this class is the fatigue class" treatment heck even give them that shrine thing from Rastakhan that has attack equal to your armor as a legendary 9/10 mana card so that Control warrior can finish the game, instead of "hoping that your opponent fatigues", Fireplume's heart warrior (can't o longer say quest warrior for classes with multiple quests), was amazing because you were delaying the game until you could get the Ragnaros hp to kill your opponent with, bring back something like that.
Shamman: More build around cards, people hate shudderwock but once blizzard dealt wih the infinite combo, it literally became the best designed shamman card period, you play your strategy slowly building up to a powerful shudderwock and there are so many things that you can do with, it, you can use it as a second N'zoth or a Jade count enhancer that also fills the board or you can do some wacky thing with a cards that increase its attack like Midnight Drake with battlecries and have it become be a Super C'Thun or have it gain charge with one of the gadgetzan hog riders, heck Bomb shudderwck shamman or using shudderwock as a second yogg is not unheard of either , the thing is that shuddewock is not instantaneously and "i win" card that you just mindlessly add to your deck but it can become one as long as you build your deck properly and build up your strategy during the match, maybe have some legendary minions that as a battlecry uses the effects of Dr cards that you have in your hand or that as a battlecry actually uses the effects of friendly Dr minions that have died this game. Also better class identity, Blizzard has forever struggled with wtf they want shamman to do or feel like
Druid: Nothing in particular, the class is well defined, and straightforward to the point that it literally does what it says in the tin, you ramp and summon big stuff or wide boards and savage roar for the win, there's a lot of combo shenanigans with druid in wild as well because ramp+insane draw power are the core prinnciple of combo decks in ANY card game if a class doesn't have access to mana cheating, but well wild druid has access to a lot of mana cheating legendaries.
Demon hunter: pretend it never happened, dont have any idea on how to fix this mess, don't want to think too much about it either, blizz was already struggling with shamman's class identity and they added one more class that willl only dilute class identity even more, the old joke of shamman being paladin 0.5 may become the same joke but for other class and demon hunter, it was a good move to get new palyers into the game and respark some interest for some players to return but in the long run i see this doing more harm than good. DH's weakness is supposed to be a class that doesn't generate extra cards, but other than that it has almost everything except for tall minion removal, it will probably be rogue 2.0 cuz lol lifesteal , or hunter 2.0 in many metas to come, i keep thinking that it was a bad idea to add another class and that the only thing it will accomplish is that it will keep stepping on the toes of other classes.
@twisted cardmaster, Warlock is a Wild class though, the class can't get singlehandedly "i win cards" because the hp will break them,, specially in standard where there are lower card pools, in fact due to how the hp works with balance, warlock will always be at its worst when the card pool is low and at its best when the card pool is wide, however all of the class cards it's been getting lately have heavy sinergy with the archetypes even when they aren't great standalone, the new warlock demon deathratle demon that summons a lifesteal, goes straight into Reno and cube warlock because it's arguably as strong as void lord, the prime? yeah, every single warlock deck but Zoo and Mechathun or malylock wants it because it's a second N'zoth/Gul'dan DK, unstable felbolt?, every control deck wants it, kel'idan the breaker, yes, it migt not be anything to write home about but an early twisting nether in a stick is a godsend in wild, so yeah, they are doing a good job, since malylock is still a viable and legendworthy deck in standard and all of their remined wild decks are fun and powerful.
Dh: id like too see a bfd. Like 20/20 for 10 kind of bfd. Dh is supposed to be about big demons, lets push the envelope.
Mage: i say double down on casino mage. I say a legendary with battlecry: turn all cards in your d3ck into random cards that cost zero. Draw until your hand is full.
Druid: 4 mana. Reveal a card in your deck Gain armor, health and cards equal to its cost. Druid has tons of mana, i say more tools to utilize that advantage would be good.
Priest: dragon legendary. 3 mana. 2/3 Battlecry: for the rest of the game you have no maximum hand size. Let priest actually use all that card creation.
Rogue: give them class specific coldlight oracle and let mill rogue be a thing again.
Warrior: i think they could really use a good infinite value tool. Maybe give them a hero power that can double their armor?
Hunter: just give them a good beast 1 drop. Its all they want ever anyway.
Shaman: how about a super toki? Say a legendary with battlecry: create 3 legendayr shaman cards from the past. It would be fun at the least.
Palladin: anything but murlocs. I like the librams, give more libram control tools.
Warlock: some nice tempo deathrattle minions would be nice.
I'll take a shot at this, some answers are really too long, i'll make this 'bullets'.
DH - no cards that should be nerfed, I'd settle for that. (result - only 4 waves of nerfs, first is after a week, and they call it improvement in listening to the people)
Druid - minions (a spell or 2 is fine), no ramp, hero, make treants a tribe
Mage - draw, minions, no casino cards (a discover or 2 is fine).
Priest - dragonS, a draw, wide own minion-affecting card, no rez.
Rogue - Stealth midrange cards, weapon. No more mana cheating. Steal would be nice, I like the theme for casual games (plus no one uses vendetta or the rusher)
Shaman - first fix basic/classic overloads, fix lady prime to 4/5 (that's not asking much), and for new - Taunt frogs spell, totem, and 'bout time we'd have a 8 or 9 cost shaman spells.
Neutral - useable lifesteal, useable deathrattle, a mech, a reverse albatross - choose you or opponent - remove 2 cards that didn't start at the player's deck. And a HL elemental minion (or totem :p )
Mage went full casino this year. YOU SHOULD NEVER GO FULL CASINO BLIZZARD, no class should base their entire strategy on pure RNG and get away with it, playing against mage is just a 05-10 min coin flip, worst class design EVER. More reliable win conditions and less RNG, pls!
Mage: Tempo mage should make a return. That or some other aggresive archetype. Mage is too expensive right now.
Druid: If they add support to spell druid, please make it less auto-piloted. Would really appreciate some support for quest druid like op said, altough those cards could become useless after the next rotation.
Shaman: More support for evolve. That and totems might make him viable. An improvement on the hero power would be good too. Blizz should avoid doing experimental stuff since that will keep shaman on the bottom.
Rogue: Call me crazy, but I would like a late-game archetype, like old Kingsbane. That's the type of rogue I like the most, but it's also the rarest type of deck in Hearthstone.
Warrior: I like the aggresive decks way more than control for this class. I say make more of that, but be careful not to make warrior overpowered.
Priest: This class is way too slow. I don't mind it being a control class, but it should take less time to finish off the opponent, like mage does.
Warlock: Make big demons great again. I'd like a control archetype that uses the board as a finisher instead of Malygos.
Mage: Absolutely more unconditional AoE. The best AoE that mage has right now is either a completely random card that comes down on 10 mana or a secret that your opponent can play around (and you still eat damage for). In general, more cards that allow mage to win the game without relying on HUGE RNG.
Priest: Holy shit, print 10 mana deal 30 damage or something. I don't want to play against a priest in the current meta. I'm tired of watching someone hunt for SOMETHING to win the game with "add a random priest minion to your hand" or "steal two cards from your opponent's deck" while throwing down infinite removal. Give them a means to end the game. And please, please stop printing Obsidian Statue with a different stat-line when the graveyard is non-existent. Priest is by no means busted right now but they are by far the least fun deck to play against IMO (priest was the first class I hit 500 wins in as a reference).
Shaman: This is a tough one because Shaman tends to be either busted or very underpowered, and I think the core of that lies in two mechanics - its terrible hero power, and the overload mechanic. The overload mechanic is insane in wild and terrible in standard. Shaman's current legal cards are a mess - elementals with no synergy, a few overload synergies, spells I guess, galakrond, battlecry, etc. etc. I don't know what exactly they should do, but they need to pick two or so of those outlets and focus on them. Its strengths are spread too thin currently.
Oh, and dumpster the Evolve mechanic. "Clown fiesta RNG" should not be class identity.
Rogue: More skill testing cards involving the combo mechanic and order. Again, right now rogue is "clown fiesta roll random card generation until you have infinite value and can win off of random garbage." Some people hated miracle, so I guess it doesn't have to be that, but something along the same lines of "you have to play control with a very limited toolset and if you succeed you go off."
Druid: More honest ramp. Setting cards to 0 turns out to be very very powerful sometimes. Spell druid right now can just sorta... explode on turn 5 and not many classes are equipped to deal with it. Yet again it suffers from clown fiesta syndrome of "sometimes they highroll a billion King Mukla's and I can't win now." We haven't seen a super interesting choose one card in a while, I'd like to see that mechanic explored more. "Choose several" legendary/epic maybe.
Warrior: Needs an entire rework, I'm not sure what I want for it at this point. Classic set is way overtuned and it's too good at everything in every meta. Insane control cards in classic, plenty of aggro enablers... more emphasis on being at low health? It's a mechanic that's been explored like, once, and has never really been explored in the class identity (Mortal Strike).
Warlock: Handlock has always been fun, and the removal of mountain giant just kinda killed it because they didn't fill the void. It's another class that feels lost as to what it's supposed to do. Galakrond is pretty lackluster because you're caught between an aggro and midrange deck. The control tools are situational and require a lot of setup when compared to Priest's "BEGONE MINION!" cards. It has no way to generate infinite value that isn't too slow. Just pick one of these avenues and improve it. I wouldn't mind zoo if it was interesting and not just "I play creatures with good stats on curve and try to avoid board wipes lol." Suicide zoo was neat.
Hunter: I legitimately don't know how to make SMORC aggro decks interesting. I understand they need to exist or combo/lategame decks run rampant but... man, how do you make "he wins on turn 5 or autoconcedes" interesting without breaking it? Idk, more beast synergies I guess. More secrets that trigger on spells. It's the issue of Red aggro in MTG, but without the question of whether or not your bolt should hit face; it can only hit face. Something skill testing that's over-statted but gives your opponent card advantage a-la Goblin Guide? Idk.
Demon Hunter: Literally any class identity at all. It has started as a mess of "uhhhh card draw infinite gas omega aggro value???" that just sorta took over aggro roles from other classes and did it better.
Regarding Druid and 'Choose One', I'd also like to see some more cards of this type. And if the Druid quest makes it problematic to balance the power level of such cards they could instead print some 'Choose Twice' cards (like Branching Paths)
I'll do this in descending order from the classes that i care the most about to the classes i care the least about
Mage: More unconditional AoE, i said this when Yogg was played in every competititve deck regardlesss of class back in 2016 and i'll keep saying it, whenever a class feels the NEED to use yogg-like cards it's because the class doesn't have enough defensive tools that are good, nor decent AoE, and no, flamestrike doesn't cut it, it may have been good in Arena but it's always been a mediocre card in constructed that you run because there's nothing better.
Rogue: reprint/retrain Vilespine Slayer, or have more class specific tutors for rogue cards, wit Galakrond nerfed rogue has to go back to a pure tempo deck, and since blizzard, wants rogue's class identity to be weak to wide boards and not have access to AoE but it hardly has anything worth mentioning when it comes to giant slayers now that Walk the Plank and vilespine are out of standard
Priest: I'm satisfied with Priest atm, can't really think about something other than stronger mid-range minions, i've always wanted a Mad Scientist like priest card that could play Shadowform i from your deck instead of secrets, but Blizzard doesn't like shadowform and they dont like cards mentioning other specific cards, mmaybe a 2 mana deathrattle that casts a 3 cost spell from your deck when it dies?
Hunter; i'm in a love/hate relationship with hunter, WIld hunter has probably the most interesting decks in the game imho, Even hunter, Deathrattle hunter either the Big beast or egg Variant, Secret hunter, all variants of spell hunter, Malygos hunter, Unseal the Vault hunter, and the wacky Otk decks you can pull off with Knuckles+Goblin Prank and/or Leorokk, heck i've otked with Gahz'rilla because there are enough cards that allow players to pull it off now, Sadly those decks are more of a happy coincidence created by player experimentation since for standard Blizzard doesn't really see hunter as a class that should do something other than go face with beasts so it keeps getting some weird aggressive beast support.
Warlock: Nothing, warlock may not be competitive in standard right now outside of quest malylock, but the thing is that Blizzard has learned how to deal with its hero power , Blizzard now knows how to print amazing synergestic warlock cards that aren't good on their own but have high sinergy potential in order to work alongside the heropower but not get broken by it, Plot twist and SUpreme archaelogy are amazing examples, they were mocked off because on paper theya re weak, but they are staples of any warlock combo deck either win wild or standard, while Kel'idan the breaker does everything warlocks like to do and with and added Bonus if you dra wit, Unstable felbolt is this card that's amazing as long as you aren't using it in a Zoo deck, so it doesn't really get broken by the hero power, then there's the discolock support, dark portal, the prime and enhanced dreadlord, all of them with their uses.
In other words Blizzard has learned that the way of warlock is the way of lateral powercreep, so for warlock please keep doing a good job Blizz!
Paladin: the thig with Pala is that the current Blizzard team seem to be avid fans of DND and want their Paladin to feel Paladin/Cleric concept of DND, where instead of Paladins that are pure light and lawful good, you have tons of different archetypes with different domains that different paladins champion, paladin of conquest, Paladin of vengeance, Paladin of redemption, Paladin of the crown, Paladin of plants(no, seriously, this exists*), Paladin of vindictive holy radiant damage and finally the Oathbreaker Paladin which i'm pretty sure that's where Blizzard took its inspiration for making mummies since the oathbreaker paladin is a champion of undead, Blizzard wants paladins to champion different stuff and that's why we have gotten a paladin of murlocs and a Paladin of mechs and the s, which have had their time in the spotlight as well as the silverhand paladin , but the Paladin that champions dragons and the oathbreaker that champions undead have never had their time in the spotlight So yeah good dragon support and reborn minions for paladins, and hero cards that bolster or enhance the tribe that you are currenlty supporting because since it is a Paladin and it's championing something it would make sense if the Paladin class had wider access to hero cards than any other class, in fact doctor boom mad genius should probably have been a Paladin hero instead of a warrior hero
*just watch this
Warrior: For the love of god give Warrior some sort of high mana or build/up finisher for control, Warrior already has a lot of good control tools, but the crux of the matter is that we are basically forec to play aggressive warrior decks and no one plays control Warrior because it doesn't get finishers, yes you still have access to the old Alex one turn gromm the following turn with a 3 attack weapon equiped, but this no longer cuts it, stop giving it the, "this class is the fatigue class" treatment heck even give them that shrine thing from Rastakhan that has attack equal to your armor as a legendary 9/10 mana card so that Control warrior can finish the game, instead of "hoping that your opponent fatigues", Fireplume's heart warrior (can't o longer say quest warrior for classes with multiple quests), was amazing because you were delaying the game until you could get the Ragnaros hp to kill your opponent with, bring back something like that.
Shamman: More build around cards, people hate shudderwock but once blizzard dealt wih the infinite combo, it literally became the best designed shamman card period, you play your strategy slowly building up to a powerful shudderwock and there are so many things that you can do with, it, you can use it as a second N'zoth or a Jade count enhancer that also fills the board or you can do some wacky thing with a cards that increase its attack like Midnight Drake with battlecries and have it become be a Super C'Thun or have it gain charge with one of the gadgetzan hog riders, heck Bomb shudderwck shamman or using shudderwock as a second yogg is not unheard of either , the thing is that shuddewock is not instantaneously and "i win" card that you just mindlessly add to your deck but it can become one as long as you build your deck properly and build up your strategy during the match, maybe have some legendary minions that as a battlecry uses the effects of Dr cards that you have in your hand or that as a battlecry actually uses the effects of friendly Dr minions that have died this game. Also better class identity, Blizzard has forever struggled with wtf they want shamman to do or feel like
Druid: Nothing in particular, the class is well defined, and straightforward to the point that it literally does what it says in the tin, you ramp and summon big stuff or wide boards and savage roar for the win, there's a lot of combo shenanigans with druid in wild as well because ramp+insane draw power are the core prinnciple of combo decks in ANY card game if a class doesn't have access to mana cheating, but well wild druid has access to a lot of mana cheating legendaries.
Demon hunter: pretend it never happened, dont have any idea on how to fix this mess, don't want to think too much about it either, blizz was already struggling with shamman's class identity and they added one more class that willl only dilute class identity even more, the old joke of shamman being paladin 0.5 may become the same joke but for other class and demon hunter, it was a good move to get new palyers into the game and respark some interest for some players to return but in the long run i see this doing more harm than good. DH's weakness is supposed to be a class that doesn't generate extra cards, but other than that it has almost everything except for tall minion removal, it will probably be rogue 2.0 cuz lol lifesteal , or hunter 2.0 in many metas to come, i keep thinking that it was a bad idea to add another class and that the only thing it will accomplish is that it will keep stepping on the toes of other classes.
@Infirc
So the fact that Warlock is the third worst class in standard now, is a "good job" for you?
@twisted cardmaster, Warlock is a Wild class though, the class can't get singlehandedly "i win cards" because the hp will break them,, specially in standard where there are lower card pools, in fact due to how the hp works with balance, warlock will always be at its worst when the card pool is low and at its best when the card pool is wide, however all of the class cards it's been getting lately have heavy sinergy with the archetypes even when they aren't great standalone, the new warlock demon deathratle demon that summons a lifesteal, goes straight into Reno and cube warlock because it's arguably as strong as void lord, the prime? yeah, every single warlock deck but Zoo and Mechathun or malylock wants it because it's a second N'zoth/Gul'dan DK, unstable felbolt?, every control deck wants it, kel'idan the breaker, yes, it migt not be anything to write home about but an early twisting nether in a stick is a godsend in wild, so yeah, they are doing a good job, since malylock is still a viable and legendworthy deck in standard and all of their remined wild decks are fun and powerful.
@Infirc
"Warlock is a Wild class though"
There's no such thing!
Dh: id like too see a bfd. Like 20/20 for 10 kind of bfd. Dh is supposed to be about big demons, lets push the envelope.
Mage: i say double down on casino mage. I say a legendary with battlecry: turn all cards in your d3ck into random cards that cost zero. Draw until your hand is full.
Druid: 4 mana. Reveal a card in your deck Gain armor, health and cards equal to its cost. Druid has tons of mana, i say more tools to utilize that advantage would be good.
Priest: dragon legendary. 3 mana. 2/3 Battlecry: for the rest of the game you have no maximum hand size. Let priest actually use all that card creation.
Rogue: give them class specific coldlight oracle and let mill rogue be a thing again.
Warrior: i think they could really use a good infinite value tool. Maybe give them a hero power that can double their armor?
Hunter: just give them a good beast 1 drop. Its all they want ever anyway.
Shaman: how about a super toki? Say a legendary with battlecry: create 3 legendayr shaman cards from the past. It would be fun at the least.
Palladin: anything but murlocs. I like the librams, give more libram control tools.
Warlock: some nice tempo deathrattle minions would be nice.
Galavant Animation
Maybe im the onlyone who wants a new hero for the rogue class ??? LUL
I'll take a shot at this, some answers are really too long, i'll make this 'bullets'.
DH - no cards that should be nerfed, I'd settle for that. (result - only 4 waves of nerfs, first is after a week, and they call it improvement in listening to the people)
Druid - minions (a spell or 2 is fine), no ramp, hero, make treants a tribe
Mage - draw, minions, no casino cards (a discover or 2 is fine).
Warrior - midrange 4-6 cost cards, no bombs.
Hunter - draw, secret, beast, deathrattle mech, dragon, weapon, hero. Brann to cost 8
Priest - dragonS, a draw, wide own minion-affecting card, no rez.
Rogue - Stealth midrange cards, weapon. No more mana cheating. Steal would be nice, I like the theme for casual games (plus no one uses vendetta or the rusher)
Warlock - low/high-cost discard, wide buff, discover.
Shaman - first fix basic/classic overloads, fix lady prime to 4/5 (that's not asking much), and for new - Taunt frogs spell, totem, and 'bout time we'd have a 8 or 9 cost shaman spells.
Neutral - useable lifesteal, useable deathrattle, a mech, a reverse albatross - choose you or opponent - remove 2 cards that didn't start at the player's deck. And a HL elemental minion (or totem :p )
Mage went full casino this year. YOU SHOULD NEVER GO FULL CASINO BLIZZARD, no class should base their entire strategy on pure RNG and get away with it, playing against mage is just a 05-10 min coin flip, worst class design EVER. More reliable win conditions and less RNG, pls!
I agree with most of what OP said.
Mage: Tempo mage should make a return. That or some other aggresive archetype. Mage is too expensive right now.
Druid: If they add support to spell druid, please make it less auto-piloted. Would really appreciate some support for quest druid like op said, altough those cards could become useless after the next rotation.
Shaman: More support for evolve. That and totems might make him viable. An improvement on the hero power would be good too. Blizz should avoid doing experimental stuff since that will keep shaman on the bottom.
Rogue: Call me crazy, but I would like a late-game archetype, like old Kingsbane. That's the type of rogue I like the most, but it's also the rarest type of deck in Hearthstone.
Warrior: I like the aggresive decks way more than control for this class. I say make more of that, but be careful not to make warrior overpowered.
Priest: This class is way too slow. I don't mind it being a control class, but it should take less time to finish off the opponent, like mage does.
Warlock: Make big demons great again. I'd like a control archetype that uses the board as a finisher instead of Malygos.
You're not, but don't count on that.
Mage: Absolutely more unconditional AoE. The best AoE that mage has right now is either a completely random card that comes down on 10 mana or a secret that your opponent can play around (and you still eat damage for). In general, more cards that allow mage to win the game without relying on HUGE RNG.
Priest: Holy shit, print 10 mana deal 30 damage or something. I don't want to play against a priest in the current meta. I'm tired of watching someone hunt for SOMETHING to win the game with "add a random priest minion to your hand" or "steal two cards from your opponent's deck" while throwing down infinite removal. Give them a means to end the game. And please, please stop printing Obsidian Statue with a different stat-line when the graveyard is non-existent. Priest is by no means busted right now but they are by far the least fun deck to play against IMO (priest was the first class I hit 500 wins in as a reference).
Shaman: This is a tough one because Shaman tends to be either busted or very underpowered, and I think the core of that lies in two mechanics - its terrible hero power, and the overload mechanic. The overload mechanic is insane in wild and terrible in standard. Shaman's current legal cards are a mess - elementals with no synergy, a few overload synergies, spells I guess, galakrond, battlecry, etc. etc. I don't know what exactly they should do, but they need to pick two or so of those outlets and focus on them. Its strengths are spread too thin currently.
Oh, and dumpster the Evolve mechanic. "Clown fiesta RNG" should not be class identity.
Rogue: More skill testing cards involving the combo mechanic and order. Again, right now rogue is "clown fiesta roll random card generation until you have infinite value and can win off of random garbage." Some people hated miracle, so I guess it doesn't have to be that, but something along the same lines of "you have to play control with a very limited toolset and if you succeed you go off."
Druid: More honest ramp. Setting cards to 0 turns out to be very very powerful sometimes. Spell druid right now can just sorta... explode on turn 5 and not many classes are equipped to deal with it. Yet again it suffers from clown fiesta syndrome of "sometimes they highroll a billion King Mukla's and I can't win now." We haven't seen a super interesting choose one card in a while, I'd like to see that mechanic explored more. "Choose several" legendary/epic maybe.
Warrior: Needs an entire rework, I'm not sure what I want for it at this point. Classic set is way overtuned and it's too good at everything in every meta. Insane control cards in classic, plenty of aggro enablers... more emphasis on being at low health? It's a mechanic that's been explored like, once, and has never really been explored in the class identity (Mortal Strike).
Warlock: Handlock has always been fun, and the removal of mountain giant just kinda killed it because they didn't fill the void. It's another class that feels lost as to what it's supposed to do. Galakrond is pretty lackluster because you're caught between an aggro and midrange deck. The control tools are situational and require a lot of setup when compared to Priest's "BEGONE MINION!" cards. It has no way to generate infinite value that isn't too slow. Just pick one of these avenues and improve it. I wouldn't mind zoo if it was interesting and not just "I play creatures with good stats on curve and try to avoid board wipes lol." Suicide zoo was neat.
Hunter: I legitimately don't know how to make SMORC aggro decks interesting. I understand they need to exist or combo/lategame decks run rampant but... man, how do you make "he wins on turn 5 or autoconcedes" interesting without breaking it? Idk, more beast synergies I guess. More secrets that trigger on spells. It's the issue of Red aggro in MTG, but without the question of whether or not your bolt should hit face; it can only hit face. Something skill testing that's over-statted but gives your opponent card advantage a-la Goblin Guide? Idk.
Demon Hunter: Literally any class identity at all. It has started as a mess of "uhhhh card draw infinite gas omega aggro value???" that just sorta took over aggro roles from other classes and did it better.
CRUISIN YEEEAH! CRUISIN USA!
Regarding Druid and 'Choose One', I'd also like to see some more cards of this type. And if the Druid quest makes it problematic to balance the power level of such cards they could instead print some 'Choose Twice' cards (like Branching Paths)
Mage: Moah Casino
Rogue: Moah 0 Mana Minions
Priest: Moah Resurrect mechanics
Hunter: Moah Charge Beasts
Warlock: Moah Boardclears
Paladin: Moah Murlocs
Warrior: Moah Miniontriggers
Shaman: Moah Evolve Stuff
Druid: Moah Ramp Stuff
DEMON HUNTER: Moah......MOAH !!!