My fav is FFX, and unlike most FF newbs, which I am, I feel they are decent reasons. (I've played FF, FF2, FF6, FF7, FF8, FFX, and FFX-2)

-I think the improved graphics and voice acting that came with the PS2 gave a more immersive, believable experience.

-I absolutely LOVED FFX's battle system. Whereas the previous 5 or 6 had ATB, which you had to be quick and alert, CTB was really more relaxed without sacrificing strategy and a little bit of thinking. In FF7, I had to lean forward, open my eyes, and constantly pay attention to the bars and who's turn it was, and such. FFX....just sat back and relaxed in nearly every battle.

-I feel it had the best story. Not the most original, but extremly immersive, believable, and full of those tear-jerking moments.

-I never thought anything could be as good as the soundtrack to Castlevania:SotN, yet FFX was.