Okay...
You've got a 360 and no PS2, right? I'll try to keep the suggestions for 360.
First off... Lost Odyssey. One of the best RPGs I've played on the 360. Also, main protagonist is awesome.

Blue Dragon. Good game... like Lost Odyssey in that it's a very traditional JRPG.
Eternal Sonata. I've got it on PS3 but it also comes on 360. Man... so beautiful. And different. And awesome.

Mass Effect. Not sure if you've played it. If not, do. It's... yeah. All the hype is deserved. XD
Fable II. Very easy to get into, and if you like Oblivion you should like this. (similar setting, etc.)
The Last Remnant was decent... but nothing stellar. Almost felt like an RTS to me. (take that for what you will)
And.
Final Fantasy XIII.
Just cuz it's gonna own everything else. <_<