Final Fantasy X was sick. But it suffered in my opinion to the Final Fantasy 7 effect of not having a definitive and satisfying ending. Final Fantasy X-2, although horrible in its storyline, rectified the crappy ending of X by giving us the proper feel good ending we wanted throughout the entire original game. Kinda like Final Fantasy Advent Children finally gave us the closure that made sense without giving us a seeming cliffhanger that we had for 7's ending. But unfortunately those two games by themselves had lackluster endings that ruin the overall experience I think.
Final Fantasy XI is just an MMORPG. Nothing else can be said about it.
Final Fantasy 12 is largely forgettable. Lackluster storyline with poor character development and it was over too quick.
Hopefully when Final Fantasy 13 comes out, it'll be a classic like Final Fantasy X. I dunno it just has that look and feel of the epicness you saw from the FFX promos.
But why the FUCK does Square-Enix refuse to remake FF7 for the next gen consoles? Do they not see that a FF7 remake would make them a fuck ton of money?