Since the PS3 isn't out yet, so the 360.
In all seriousness, each has something good to offer better than the other. The 360 has a pretty good library of games, with more diversity than was offered on the original Xbox, and the lower price of $400. The PS3 will have an EXCELLENT library of games (cmon, they already have FF13, DMC4 and MGS4, what else do you need?), but the higher price tag of $500, and you'll probably end up needing to buy a HDD for another $100. In conclusion....
Nintendo Revolution.