It's all going to depend on what games you like playing and your level of patience before exclusive rights to certain PS3 titles end (i.e. Metal Gear Solid, Final Fantasy, etc) so the Xbox 360 can make them. Some might not be available ever on any system other than PS3 (Final Fantasy series) or later on the PC. It all boils down to games, as each system is going to be hella powerful enough to give you plenty of eye candy.
I myself played a lot of vg's as a kid but there are few games today that can hold my interest, so I'm going to wait until all the new systems are out before considering buying any of them. Nintendo's new one looks to be the most unique out of the three, using a wireless controller that looks like a tv remote that is motion activated.
As I said before though, it's gonna boil down to what games you want to play, or else buy all three.