FFIV: Kain
FFIV The After Years: Kain, again :P but I also really like how Edge matured.
FFV: Faris
FFVI: Locke, who's my favorite FF character ever.
FFVII: Tifa
FFVII Crisis Core: Zack
FFVIII: Rinoa
FFIX: Zidane
FFX: Tidus
FFX-2: Rikku
FFXII: Balthier
FFXIII: Lightning
FFXIII-2: Hope
FFXIII Lightning Returns: Lightning
FFXV: Noctis