VI - Never used Mog, Umaro, Setzer, Relm, or Strago. The others just appealled to me more I guess.

VII - Cait Sith - annoying cat
Tifa, Aerith, Yuffie - I was a sexist pig and thought only men could save the world.

VIII - Rinoa - Just annoyed me.
Selphie - Also annoyed me.

IX - Eiko, Quina, Garnet - I used mostly the physical fighters (except for Vivi, who is just cool.)

X - Everyone except Auron, Tidus, or Lulu.

XII - Everyone except Vaan, Balthier, Fran, and Basch. They were my fav. characters in that game (Basch especially).