Alright, going to try to offer some data here... hopefully the thread doesn't explode.
The number of Japanese RPGs is actually pretty close between the 360 and the PS3, though keep in mind two of the better Japanese RPGs for the PS3 are strategy RPGs, meaning the games play out more like Final Fantasy Tactics, Shining Force, or Fire Emblem than they do a traditional JRPG -- the emphasis is on a large cast of charaters and large scale battles.
Xbox 360:
Resonance of Fate
Final Fantasy XIII
The Last Remnant (An underrated game!)
Infinite Undiscovery
Tales Of Vesperia (Great game, especially if you like anime inspired graphics and story! Also has four player local coop for battles! Not when you're exploring, though.)
Lost Odyssey
Blue Dragon
Magna Carta 2
Star Ocean 4
Eternal Sonata
PS3:
Resonance of Fate
Final Fantasy XIII
Disgaea 3
White Knight Chronicles (Another underrated game. If you want to try a traditional JRPG with online coop, this is probably the first game ever to offer it. Be warned: The story is pretty cheesy.)
Folklore
Demon's Souls (If you count it as a JRPG. It's more like 3D Zelda meets Diablo in a medieval Japanese survival-horror... or something.)
The Last Rebellion (Horrible game, from what I've heard...)
Valkyria Chronicles
Star Ocean 4 International Edition (has some extras, like more party members, that the 360 version didn't get.)
Eternal Sonata (Also has extras that the 360 version didn't get. Two other characters, more story, I think?)
Hope this list is a force of good, and not evil, in helping you decide the current standing of the consoles and their JRPGs. :)
