Imma go with the 360. I have a PS2, but the times when I used it I was too young to...well appreciate it enough, plus on top of that I never really have any of the classics so the whole experience was lost on me (I have Dogs Life for Christ's sake, does that say anything?).
The 360 however I've played through my entire teenage years and it has some of my favourite games on it, even though I don't have an extensive library, I don't really need one with all the awesome games I have that I can play over and over.
Though I fear it will be obsolete come the new console seeing how quickly the last generation died out under the 7th, but oh well, at least 360 game prices will drop.