I loved FFVII. It's my favorite. Great gameplay, and I really like the story and characters (*drool* Vincent...

). Anyway, I wish I still had my copy, I've been itching to play for weeks, but my brother lost it (or destroyed it... not too sure.)
I never really got into FFVIII. I rented it once, but it bored me, so I never bothered playing it through. Maybe I will, someday.
I really like FFIX. Good story and game play. Some of the characters were annoying, but hey, it has Vivi. So everything balances out.
FFX is close up there with FFVII. Amazing graphics, great story line, fantastic characters and cool game play. I personally love the Sphere Grid. And I really like Blitzball (I know not many do... and I'm not one for mini-games, but I really liked it). Plus, the ending to the game was amazing.
FFX-2... eh. It had potential, if you just through out the fru-fru story line, there were some parts that were actually good. The new characters (Baralai, Gippal, Nooj, Paine) were awesome, and in my opinion, kind of wasted in this game. And they could have worn more clothing...