I played Final Fantasy VII and VIII religiously. Deep story, and great twists and gameplay. FFIX lost me. Just wasn't very interesting to me...played Xenogears, instead.
FFX was a great, great game, but not quite as good as VII. Might put it either on par, or just below VIII. Didn't play XI or XII, as XI was online only and looked dumb, to boot, and XII just kinda went under the radar, but this new one looks pretty sweet. May give it a whirl.