I think my favorites thus far are VII and V. I liked II back in the day as well.
VII has a pretty good story and takes quite a long time. In fact I still haven't finished the game, even though I've put over 100 hours into it! Well I just need the last part, but I was leveling up my characters job skills, hehe.
I'm still in the middle of V, but I like it so far. I'm playing the PS2 version. I'm also currently playing the re-make of III on the Super Famicom. It's also pretty good, but I'm not as into it as I was II awhile back.(I also played 1 a long time ago too)
I also have VI (Super Famicom), but I'm not going to play it until I clear V probably. I also bought VIII, but I haven't gotten around to playing it, yet. I also need to borrow IV(DS) from my GF so I can give that a go through.
starcraft: "I and every PS3 fanboy alive are waiting for Versus more than FFXIII.
Me since the games were revealed, the fanboys since E3." 
Skeeuk: "playstation 3 is the ultimate in gaming acceleration"
Essay Pro