Sokka - You could say I'm a Sokka fangirl. Why? Well, I kind of see a bit of myself in him. Meat, sarcasm, skepticism, logic, science... You get the idea, although he's much funnier than I am. ;) He's also one of the most flawed yet still likeable characters, which is always a plus. Perfect characters are excruciatingly dull.
Zuko - Once more, he's the imperfect yet redeemable character. He changed more than anyone else, in my opinion.
Azula - If I had to choose between being a psychopath and being a sociopath, I would pick sociopath. Siriusly, Azula is the single most intelligent character in the show, bar none. She is in fact flawed, and she has a complicated interior, although I think she gets her way a little too much.