Dragon Age Origins and Skyrim while both superb are not the kind of games I would play on a console, due to controls, though mostly you miss out on probably the best mod community out there. Mass Effect on the other hand, now that, I see. Mass Effect happens to be one of the most exciting video game series I ever played, the first one being my favorite. It managed to create quite a rich and fascinating lore in such a short time, thus huge recommendation. I'm not quite sure if you can find the first one outside the trilogy pack as it was an XBox 360/PC exclusive, though the trilogy pack is rather cheap for what it offers.

As someone who bought PS3 recently I found out that PS3 does not have many appealing RPG's, unless you're into generic JRPG's, there are tons of them. I know it's not an RPG but seeing as you are a MGS fan just buy MGS 4: Guns of Patriots, one hell of a game.