To concur with a couple of others, I'd definitely have to go with Lost Odyssey. This game is very very in depth, and like another member said, it is
well written, and the Thousand Year Memories make great but (truly) tear-wrenching stories. The whole of the game is very sad, so don't expect any
pep. But it is by far the best (old-school) RPG out there. [yes I consider Fallout 3 a kind of new-school RPG] Both are great, but if you want an RPG
with TONS and TONS of storyline, and are willing to both watch the cutscenes and read through allll the memories (which read like a story-telling
book) then by all means Lost Odyssey is my recommendation for you, my friend.
If you're looking for a non-final-fantasy-esque type of RPG:
Infinite Undiscovery
The Last Remnant
Oblivion
Fallout 3
Blue Dragon
Eternal Sonata (very graphically BEAUTIFUL game)
Granted: I have still to get my hands on Final Fantasy XIII so my opinion is, if not biased, then outdated.
Hope I helped!!