Hearthpwn

Oooh, I love this thread idea. Probably Majordomo Executus for me. I won one game as Ragnaros with my Control Warrior deck. But I haven't played with it since. Oh man, but I want to....

TOO SOON EXECUTUS. YOU HAVE SUMMONED ME TOO SOON.

Make sure you like the deck you're sticking with and that it suits your play style. Do you like playing control, combo, or aggro? Also, make sure the deck is good enough against the current decks you're seeing (as judged by someone other than you). Then just keep at it. It really does take a long time to get good at a particular deck. (Even if you feel like your opponents just keep getting cheap wins)

Also, if there are certain decks that you feel keep beating you, such as Combo Druid or Face Hunter, maybe try those decks out. Worst case is you'll get a better idea of how they work, and be able to play against them better.

Just have to point out, the title of this thread is basically the definition of a leading question. Maybe if you want to promote discussion in the future, don't ask a question that already assumes the answer...

I think any of the options you listed are reasonable. As was mentioned, the Black Knight is great right now.

Just one thought, if you like control decks, control warrior is fun, and Grommash Hellscream would be another card to consider then. Probably other options are better, but just an idea.

I think the phrasing on your poll questions is pretty biased. You've already assumed in your question that no one wants to replay the Naxx bosses and make it sound like there is no reason to.

Personally, I really enjoy Naxx as it is. The heroic mode in particular is a fun challenge (especially if you don't look for deck lists online or try and come up with new ways to beat a boss). The whole adventure mode has a lot of character and is really enjoyable. I've replayed some of the class challenges and heroic bosses because I find them enjoyable.