As has already been said, all 3 systems have their pros and cons; their good games and their bad games, and that will always be the case. Personally, I have an Xbox and I don't really have the money to go buying a PS2 and/or a GameCube. IMHO, I think the Xbox has a better lineup of games than the PS2, with there being plenty of Xbox exclusives (Halo/2, Project Gotham, Ninja Gaiden, and not a lot of PS2 exclusives - most of the games are out on the Xbox too with the exception of GTA and some other stuff. And with the multi-format games, 99% of the time you'll get a better game on the Xbox, whether it be graphics or whatever. I also find the PS2 controller too small and some of the buttons in awkward places (the shoulder buttons are a pain to reach in my opinion). But the PS2 is the man in the street's console of choice, and will undoubtedly stay that way until the next generation is upon us.
But as I say, you'll always get people who like and dislike each console, it's really down to personal preference for whatever reason.