I chose Wii; it has a lot of great titles (Super Smash Bros. Brawl, Legend of Zelda: Twilight Princess, No More Heroes, much more) and it's really innovative. I do have a bit of trouble getting it to register my Wiimote movements at times though.
My second favorite is the PlayStation 3. It's a pretty solid system with some good games... It just needs more of those good games. ._. *only has four for it, excluding one PSN game*