Oh wow, after making my detailed earlier post, Final Fantasy XIII got announced for Xbox 360! This changes everything.
Best Console Exclusive Rpg's for each three home consoles:
Xbox 360: Blue Dragon, Eternal Sonata, Lost Odyssey
Xbox 360(upcoming): Tales of Vesperia, Infinite Undiscovery, Fable 2, Cry On
Playstation 3: Folklore
Playstation 3(upcoming): Disgaea 3, White Knight Chronicles
Wii: The Legend of Zelda: Twilight Princess, Super Paper Mario(platformer rpg), Fire Emblem: Radiant Dawn, Final Fantasy Fables: Chocobo's Dungeon
Wii(upcoming): Tales of Symphonia: Dawn of the New World, Next Zelda Game(unannounced but will be coming)
...I removed Final Fantasy XIII and Final Fantasy Versus XIII from PS 3's upcoming top console exclusive rpg list. I think that FF V XIII will eventually be announced for a Xbox 360 release.
PS 3 has Disgaea 3 and White Knight Chronicles coming out. How popular is Disgaea 3 though? I believe that White Knight Chronicles will be as popular as the other big traditional rpg's I listed.
Huge news! I hope both versions of Final Fantasy XIII are almost exactly the same. I will probably get the Xbox 360 version, unless there's something special on the PS 3 version.