I'll make as list from the FF games I have played:

FFTA: Ritz
FFVII: Aerith or Tifa(that's such a hard decision)
FFVIII: Rinoa,who else!
FFIX: Princess Garnet
FFX: Yuna, she was so much better in this one.
FFX-2: Rikku, she got more mature since the last game. "oh, poopie!"...nevermind.