For me its the xbox 360 cause its what i play the most and if i had a good enough computer i would use my computer to play games, but other then that the xbox 360 is my favorite next-gen console
I'll have to say PS3... Mainly because it's the only one I play at the moment despite having an 360 and a Wii. The Wii, I don't have any decent games for it due to my neglect and the 360 is hooked up to a crappy tv, so I'm waiting to put it on something better before I mess with it again.
I've been a Sony supporter since PlayStation 1, so the PS3 is my fave current next-gen gaming system. I get to be in touch with people from around the world, enjoy my vast collection of music and most of all, I just love the trophy support that comes with the games I play, makes me go the extra mile to get the platinums in various games for all the hours I've put in to be rewarded for them is the best part when you hear that lovely 'trophy' sound pop up.