FF8.
i haven't play it in forever, but i still have fond memories of it- the characters were good, none of them were overbearing characterwise; the Draw/Junction system was good and didn't allow for abuse; i loved the final boss-- randomizing the party every turn.

FF7 was overhyped.
FF9 was a close second, but i hate Quina.
FFX was horrible. i played straight through it, just to play the damned game, and i regret every minute of it.
I liked FF6, but it was a gameboy edition, and playing handhelds is my bane- all i remember was rescuing Celes at the opera, and then landing on an island where enemies spammed Acid Rain... if FF6 ever comes to the PSP or even PSN, then maybe i'll get it.
FF12 was boring. what's the point in having a "main hero" that doesn't have anything to do with the actual story? i even forgot how Vaan got roped into joining Balthier and Fran to rescue Ashe and Basch...
FF13- i got as far as the Odin fight and quit. Hope (ie: Deadweight) was already my least favorite character [get him to dye his hair and give him some eyeliner, and some psuedo-punk clothing and he'd be fully emo!], but none of hte other characters caught my attention-- so already my patience wore thin. When Odin killed my party in 10 seconds- i was fully fed up.
I only remember getting lost in the first Final Fantasy, not getting very far in FF2 [ala the FF-Origns game] and i don't remember anything from the FF4 game (ala that Chrono Trigger pack- either Anthologies or Chronicles)...
so, by default, FF8.