Hearthpwn

I played variations of this deck from rank 17 to legend. With time, I found out how important some cards are, which I previously thought were only "okay". Notably, Nesting Roc is so strong that it often autowins you matchups against SMOrc decks such as Pirate Warrior and Token Druid.

This list contains a copy of Hungry Crab and Golakka Crawler as tech cards against frequently played archetypes on rank 5 and higher: Aggro and Midrange Murloc Paladin and Pirate Warrior + all Rogues. These cards can be substituted without a drawback depending on the meta.

 EDIT (28.4.2017): 1x Fire Fly replaced by 1x Timber Wolf.

Commentary on cards plus replacements:

1 drops:

 Alleycat - best card to cast on turn 1, especially if you go first; double 1/1 bodies perfectly synergize with Crackling Razormaw and Scavenging Hyena and later with Nesting Roc. No replacement.

Fire Fly - great value card, especially to fill out your curve. Possible to replace with Timber Wolf or Fiery Bat if you prefer beast synergy. Fire Fly gets value if you also run Dire Wolf Alpha.

Jeweled Macaw - great resource card! draw first with Macaw and see what you get before you play other stuff on that turn (if you plan on playing Macaw). No replacement.

Hungry Crab - tech against popular Murloc decks, can be replaced by Fiery Bat or Dire Wolf Alpha.

Timber Wolf - nifty 1-drop (made the cut over Fiery Bat) and replaced for me one of the 2 orginal copies of Fire Fly. You don't want to play this on turn 1; instead, you play it to significantly increase your damage on the board (to get through taunt or make good trades with your board; to buff a big Unleash the Hounds; to SMOrc and kill your opponent/setup (potential) lethal for next turn). Very flexible card, I love it!

2 drops:

Golakka Crawler - tech against Pirate Warrior, Quest and Miracle Rogue and Token Druid, can be replaced by Dire Wolf Alpha or possibly Ravasaur Runt.

Crackling Razormaw - the card that almost singlehandedly made Hunter great in Un'goro. Cannot be replaced.

Scavenging Hyena - the combo card of this deck together with Unleash the Hounds and Dire Wolf Alpha if you run it. No replacement.

Kindly Grandmother - powerful card in terms of value. Can be coined out at turn 1 if you have Crackling Razormaw in hand to usually to get Poisonous, +3 Attack or +1/+1 from Adapt and deal with opponent's 2-drop. Synergy with Tundra Rhino. There is no replacement for this card, however, if you don't have Karazhan adventure, you can run Dire Wolf Alpha, Golakka Crawler or possibly Knife Juggler.

3-drops:

Animal Companion - typical card for Midrange Hunter, provides versatility and is solid. No reason to replace.

Kill Command - only direct damage spell of this deck. Usually you want to save it for lethal turn. If you already lost the board, don't forget to keep a cheap best in your hand so that Kill Command deals 5 damage. Can also be used to get rid of minion threats or taunts to preserve your board. No replacement.

Eaglehorn Bow - great to get tempo on turn 3, also great to SMOrc you opponent down when is low on health. Keep in your hand if you also have 1-drop and 2-drop, or 1-drop and Fire Fly, or if you go second and you have a 1-drop. No replacement.

Rat Pack - surprisingly good card, synergy with Houndmaster, Crackling Razormaw and Tundra Rhino. If you don't run Rat Pack, then you probably won't run Tundra Rhino either. Replacements: Vicious Fledgling is pretty nice (but still worse - see section "Other techs and possibilities").

Unleash the Hounds - main combo card to buff Scavenging Hyena and/or get rid of opponents board, or SMOrc opponent down after he took the board (if he has a taunt, can be efficiently combined with Crackling Razormaw to get Poisonous from Adapt. Works great with Leokk or Dire Wolf Alpha.

4-drops:

Houndmaster - key synergy card with beasts. If you have a beast on board on turn 4, it is often correct to play it. No replacement.

5-drops:

Nesting Roc - wonderful card, autowins you a game vs. SMOrc decks if you manage to get a taunt on it. Guaranteed taunt on turn 6 in combination with Alleycat.

Tundra Rhino - synergy with Kindly Grandmother, Rat Pack and Savannah Highmane. If your opponent doesn't remove it in his turn, you practically won. Don't forget that Tundra Rhino has charge himself! Can probably be replaced for second  Savannah Highmane.

6-drops:

Savannah Highmane - the top of the curve with insane value. Plays around mass removals (e.g. Brawl) as it summons 4/4 worth of stats as a deathrattle. No great replacements, but if you don't have it, try Volcanosaur. Okay to play two copies.

 

Other techs and possibilities:

Hunter's Mark - good against big taunts and minion-based control decks in general, can be swaped with Fire Fly.

Deadly Shot - good get rid of Edwin VanCleef or other op early minions. In general, questionable if worth playing (Hunter's Mark probably better now).

Dire Wolf Alpha - very good card in this deck to buff tokens, I played this card until I reached rank 5, then it got swapped for tech cards

Ravasaur Runt - alternative for Golakka Crawler, but I found difficult to get adapt on turn 2, so I don't play it anymore

Infested Wolf - I feel that it is too slow (seems equivalent to Rat Pack with worse deathrattle effect), I don't play it anymore

Tol'vir Warden - I believe it is possible to run if you also run 8+ 1-drops, therefore you play more aggressive version of Hunter

Bittertide Hydra - strong card, but depending on the matchup it may turn out to be a burden. I'm not sure about this card.

Fiery Bat - okay card, didn't make the cut for me because there are so many better 1-drops.

Tracking - definitely possible to play, perfect to look for Savannah Highmane, Crackling Razormaw or Hunter's Mark against control matchups to get value or to destroy a powerful minion. Another use is search for direct damage Kill Command, Eaglehorn Bow, Animal Companion, Tundra Rhino or Unleash the Hounds if you need to finish your opponent.

Flare - tech card against Mage; unlike other tech cards, however, this card is completely dead in other matchups. I don't recommend to run it unless Mage becomes the most frequently played class. Same goes with Eater of Secrets which I consider even worse.

Vicious Fledgling - the more aggressive deck you have, the better this card is (its Dr. 3 for Token Druid); for this type of Hunter, it could be okay, but the problem is that you absolutely want to play all the 3-drops from the original decklist. Therefore, this card would probably have to replace one of the 2-drops making your early game worse (and therefore Vicious Fledgling too). On the other hand, if you don't own all the 3-drops from the original decklist, this is a pretty good replacement.