Based on your tastes, the PS3 seems the most obvious one. You don't care for online, you don't care for halo and other fps's, so you will save at least $60 with PS3.
There are rpgs on PS3 as well, and action games like uncharted/god of war/infamous/ico&sotc/metal gear solid 4/heavy rain/ etc pretty much say PS3. You may like LBP as well (platformer)
360 is basically for online gamers who have friends on XBL or those who like halo. Remember that if you are not interested in online and buy the 360 without gold, you will never be able to try out the mp part of a game at all. Even as a trial.
Since you have a PC, most of the rpgs you are talking about are available on it anyway. ME 1 for eg doesn't work that well on the 360, but does work better on the PC. Without the need for an extraordinary PC.