my favorite game is Final Fantasy viii (8 ) as i like the characters and because it was the first game i got for playstation. i finished this game and it still has stuff im finding now like there are more Guardian force (GF) than if you just play it straight there are some hidden, some that have to be drawn out and some that need certain items to get.
Final Fantasy ix (9) i had to get imported from america and get my playstation chipped so i could play it as it was discontinued here, i haven't really played this game much as it doesn't catch me as well as the one before it. the characters are fun but the story line is a bit on the tame side.
Final Fantasy x (10) i liked the characters and the story line for this game the only issue i had with this particular game was the leveling grid i think they went down hill when they brought this in. i have completed this game as well.
Final Fantasy X-2 (10-2) again i liked this game especially because it was the first squeal to any of square enix's (squaresoft) games and some of my favorite characters from Final Fantasy x came back there was even a few camo shots of npc's (non playable character)
all in all i think all Final Fantasy games should be given a go!