Mass Effect for me. KotOR was a great series, but...I don't know. Mass Effect felt a bit more...something.
Unless it's a Male Shepard. It's like someone ate his soul or something...Also, while I love the Jedi and just about anything about them, I HATE just about everything else in the Star Wars universe. When you've got a bunch of guys who tap into the energy of the universe (I love the more meditative aspects) and fight with beams of freaking plasma, blasters, smugglers and most of the planets seen seem incredibly dull by comparison.