I own all of them and I like all of the, for different reasons. So I'll list all of them.
PS3- Ps3 has my favorite exclusives, free online, powerful, and has blu ray. Uncharted, Metal Gear Solid 4, and InFamous are all amazing games.
Xbox 360-Also powerful, has the best controller, xbox live has the best online with party chat. Great with multiplatform games, Gears of War is amazing. P.S. Gears of War 3 Beta is even better than the first :D
Wii-Super Smash Bros, Super Mario Galaxy, Zelda Twilight Princess, and Donkey Kong Country is good games.
PSP-I like Metal Gear Solid: Peace Walker for it
DS-Dual Screen, innovative, touch screen, pokemon, professor layton, pokemon, Mario bros, and well...pokemon
3DS-It has a a lot of potential, good graphics, 3D is great on it. And it has a huge library coming out this year like Zelda, metal gear, star fox, super mario bros, mario kart, Resident evil, dead or alive, cave story, and cubic ninja. And it also has games coming out like paper mario, resident evil revelations, donkey kong, and assassins creed.
