KKM: Adelbert or Gisella because I think they're both underrepresented and awesome characters. Gisella could be pulled from anywhere in canon I think but Adelbert, I'd probably choose to during the Big Cimaron arc or just before big revelation occurs. I like my men conflicted and confused!
Gisella I'd just want to play because she'd boss everyone around but then turn around and smile and be the sweetest thing ever.
X-Men: It's been a while since I've seen X-men, but I liked movie!Rogue and loved Jean Grey from cartoon canon. I think, however, I'd rather play Rogue if only because I'm not sure I'd like Jean as well upon a canon review. I do like the idea of playing older Rogue however which means I'd probably still do a review of the 1980's/90's? cartoon version.
Avatar: The Last Air Bender: I'll get back to you on this one later. I have to read up on wiki first!
Buffy the Vampire Slayer: In a perfect world, I'd app the Mayor. Hands down because I love his character so. But we weren't going for realistic or ability so there!