I'm really surprised that no one has mentioned FFXII.It had probably the most in depth story of all of the FF games plus hands down the best fighting system of all the others.Plus the characters were really original.
That said,FFVIII is still my favorite overall game(nothing beats Squall and his Gunblade) but FFX had one of the best ending I've seen for any video game.
to me (and not only to me) FFXII looked like a star wars fantasy spin off.
Vaan = Luke (I want to be a pilot, I hate the empire, at the end I wil be a Rebel against the empire)
Balthier = Ian (I'm a Skypirate I have a fast ship, I'm cool!)
Fran = Chewbecca (I'm the non-human Sidekick of the skypirate [ok this was a big improvement from star wars])
Ashe = Leila (I'm the princess of the fallen realm. I lead the rebels)
Judge Gabranth = Darth Vader (Filtered breath and speech, I'm bad and cool but in the end I will help destroying the Empire, and "Basch... I am your Brother!!!")
Let's add the sky battles fought between airships shooting laserguns and the unstoppable giant ship ... the Dark sta.... Aemh... the bahamuth...
Seriously If I were george Lucas I would sue them.