1. Thor. Surprisingly, I hadn't really thought that at any time would Thor turn out to be my fav, but somehow he did :)
2. Storm. I used her through my entire first play through.
3. Gambit. If not for the fact that he's funny, his moves are pretty tight too.
4. Hulk. Why not, his lines are actually pretty funny, and it's always fun to pick up a dude and slam him into another dude. haha