Hearthpwn

My personal favourite is ramp druid without the standard Force of Nature or Savage Roar combo, focusing instead on more consistent ramp tools like Nourish and heavy duty spells and minions.  I have tried a lot of incarnations of this over the couple years I've played hearthstone and have had the most success lately with a tempo/dragon based one with tons of board clear such as double Starfall, Chromaggus, Baron Geddon in place if the usual taunts like Druid of the Claw and Ancient of War. I found taunts really just don't work any more with today's meta of endless, high value, sticky minions.

With all the ramp options now available (2 x Innervate Darnassus Aspirant, Wild Growth and 1 x Nourish) I find the ramp hits the vast majority of the time, so all the weak 1, 2 and 3 drops, and weak spells like Wrath and Living Roots were actually diluting the power of the deck's late game. With all the board clear, ramp tools, and minions that get value as they are played, the ultra ramp concept is really starting to shine. But sadly no, Astral Communion just doesn't make the cut... it is too risky. 

I enjoy running a midrange secret mage deck with Illuminator and Kirin Tor Mage. A real interesting LoE inclusion to my deck has been Jeweled Scarab, most of the time discover provides me with even more secrets. The win/fun condition is to aggressively confuse the opponent. Fun-fact: Even in a deck full of secrets, Piloted Shredder is still a better 4-drop than Ethereal Arcanist most of the time.

Hobgoblin paladin, highlander paladin, egg-adin, dragon paladin . . . I really like paladin. And I really don't like Mysterious Challenger.

Also: Wailing Soul druid, pirate rogue, OTK priest (the Prophet Velen kind), and anything with Summoning Stone.

Dragon Warrior is pretty cool, and a bit underrated. Same goes for full-on Aggro Warrior.

The deck that I really want to work is Mech Rogue, Iron Sensei and Auto-Barber are really cool cards but overall it's just too fragile. It lacks the tempo cheat too like Mirror Entity, and an OP finisher like Antonidas or Doomhammer + Rockbiter. Clearing the board as a Rogue is always a PITA, unless you're playing Oil.

The difficult part of playing something really off-meta in Hearthstone is that on one hand, someone has tried it before and you can always find inspirations, but it's really hard to tell what's a hidden gem and what's a failed experiment from just looking at the list and playing 2-3 games on casual. There is so much that looks good on paper but really gets destroyed by bad draws or the wrong matchup. And then there's decks where you look at the list and think "how the hell can that ever win a game", until you see someone pilot it on legend level.

For example, when I first tried Freeze Mage I thought the deck completely sucks because I somehow managed to run into Control Warrior on casual twice in a row.

Recently i have been having a ton of fun with battlecry and deathrattle combos. Now i have sort of tied that all together into a mech deck and i am having a lot of fun with it

My favorite deck is a Reno priest deck that focus on value with cards like Thoughtsteal, Chromaggus and discover. I guess it is in some sense a fatigue deck, but that is not exactly the point, the idea is to outvalue your opponent and play the big minions when they are out of removal. I even play with a Mind Control, which is really powerful in this more controlish meta.

I also always wanted to make work a mech priest deck, especially now with Gorillabot (which is super strong card). But it just doesn't work.

i love playing full fatigue rogue, with ALL the removal (2 SP, 2SD, 2 cabals, 2 entomb... you get what i mean) and a couple of legendarie threats like ysera, i also enjoy playing any kind of dragon deck and mill rogue, i LOVE mill rogue i enjoyed playing patron warrior while it lasted because it was a deck that actually required skill to play

My homebrew Reno Paladin :D. Pretty competitive too

Handlock also happens to be one of my fave decks

I made my own Reno-fatigue warrior and it is so fun

My absolute favorite deck right now is the recently renamed The Mad Hatters. It's a deathrattle Hunter that I thought might be fun. Explorer's Hat has turned into a very clutch card in there, and I'll frequently spend entire late-game turns playing hats and Lock and Load. I've set fire to more hats than I can count with Feign Death and Baron Rivendare, and I'm not sure anything has ever been quite as funny to me as killing somebody with a Nerubian Egg that was just wearing so many hats at once (just picture it!) It's also a lot of fun stealing 4+ minions in one game due to an unanswered Sylvanas Windrunner

I have no idea if it will be viable in the upper eschelons of the ladder, but it's been performing pretty well on the early month climb. Almost doesn't matter, it's just so much fun.

I got Captain Greenskin and Skycap'n Kragg from packs recently and have been playing around with an aggro/pirate rogue hybrid.  Getting a couple of  Ship's Cannon working is super fun (although difficult to pull off)

my favorite deck right now is reno warlock, and dreadsteed warlock, but i ladder with a zoo, i don't have the time to ladder with these decks

I actually really love Mech mage. I love the synergy. I use a version without mad scientists and mirror entity, and instead flesh out a little bit of it's late game with a Piloted sky golem and more mid game minions like the new Gorillabot A-3, which i really do find effective.

Somemonths after naxx i tried my ow duplicate giants deck using moltens and mountains, it was literally the first deck i reached the 100 gold cap with because i had effectively lost track of time with all the fun i was having, it kind of doesn't work anymore tho since i don't have echo of medivh and the metais much faster now.

I've been having a lot of fun and a lot of success with malylock, Easily climbed from rank 16 to rank 10 in a day. I usually finish between rank 10-5 but maybe this season with this deck I can make the final push to legend :)

I love Reanimate Shaman.  The autoconcedes when you reincarnate a Kel'Thuzad are priceless.  I've also ended up with an entire board of Thaddiuses... Thaddiui?