PS3. I do have both and my Xbox 360 is now 3 years old (I think I'm lucky it's lasted that long) and I think it is dying. Games are pretty much the same for both systems except to few exclusives which don't really bother me too much so i would go ...
having played both a friends house's, i say the PS3. but i guess its not that fair since ive had a playstation since 1998 and havent really played many other consoles.