As a 360/PS3 owner, it's easy to say:
Xbox 360. (Until now at least)
JRPG on 360 (now available):
- Lost Odyssey
- Tales of Vesperia
- Infinite Undiscovery
- Eternal Sonata
- Spectral Force 3
- Blue Dragon
- Enchanted Arms
- Phantasy Star Universe
- Final Fantasy XI
Upcoming JRPG on Xbox 360:
- Final Fantasy XIII
- Star Ocean: The Last Hope
- The Last Remnant
- Apocalypse - Desire Next