I made those list (all from metacritic ) to compare both PS3/360. Loads of great RPGs are going to be released this year so the list will change every month or so. For now here it is :
360
West/Action RPGs
Mass Effect 2 = 96
The Elder Scrolls : Oblivion = 94
Fallout 3 = 93
Mass Effect = 91
Fable II = 89
Dragon Age Origins = 86
Borderlands = 84
Marvel Ultimate Alliance = 82
Marvel Ultimate Alliance 2 = 73
Sacred 2 : Fallen Angel = 71
Too Human = 65
Divinity II : Ego Draconis = 65
Risen = 58
Kingdom Under Fire : Circle of Doom = 55
Rise of the Argonauts = 54
Dark Messiah of Might and Magic Elements = 52
Two Worlds = 50
JRPG
Final Fantasy XIII = 84
Tales of Vesperia = 79
Blue Dragon = 79
Eternal Sonata = 79
Lost Odyssey = 78
Star Ocean : The Last Hope = 72
Enchanted Arms = 69
Magna Carta 2 = 69
Infinite Undiscovery = 68
Final Fantasy XI = 66
The Last Remnant = 66
Phantasy Star Universe = 64
Spectral Force 3 = 59
Operation Darkness = 46
Zoids Assault = 46
PS3
West/Action RPGs
The Elder Scrolls : Oblivion = 93
Fallout 3 = 90
Dragon Age Origins = 87
Borderlands = 83
Marvel Ultimate Alliance = 78
Marvel Ultimate Alliance 2 = 74
Sacred 2 : Fallen Angel = 70
Untold Legends : Dark Kingdom = 58
Rise of the Argonauts = 57
JRPG
Demon's Soul = 89
Valkyria Chronicles = 86
Final Fantasy XIII = 83
Eternal Sonata = 80
Disgaea 3 : Absence of Justice = 78
Star Ocean : The Last Hope International = 76
Folklore = 75
Enchanted Arms = 64
White Knight Chronicles = 64
Cross Edge = 52
Last Rebellion = 46