Well "best" is subjective but if I had to give my opinion I'd say Final Fantasy X probably had the most interesting story.
Only to be hurt by a pansy lead. I hate Tidus. I do agree it hit a good mark on the story.
Hmm....For the life of me, I can never remember 8's story.
How can you forget the overblown ridiculousness of it?
-going to a space station
-monsters on the moon (did they ever expand on that?)
-thrown into jail after ice speared you
-Laguna day dreams
-Squall and Rinoa were almost bro and sis
-Fighting ...um, hockeyplayers?
-The "we forgot playing "house" in our past - when we all lived together" like the GFs were some sort of date rape drug
-Rinoa catatonic half the game (typical main female stereotype, same with Collette a la ToS, where the F?!)
-Fighting another garden
-Fighting a fat man underneath your garden
-Your school flies and your headmaster is Robin Williams
-Theres a city bigger than more than 10x of all the towns you visited...thats kept a secret.
They chain all those together somehow.