I still prefer the PC, with high-end system, you can run games that have better framerate and graphics. Generally the PC also has more realistic titles, and if these are available on consoles as well, I prefer the PC versions controls. Rainbow Six and Ghost Recon should be played with mouse and keyboard. America's Army is a solid title for realism. Another realistic infantry game is Operation Flashpoint, the vehicle physics arent great, and the AI is cheap, though. I've always liked the PC better, but still,I love consoles.
I own a PS2 and XBOX. I prefer the XBOX.
The PS2 has some great exclusive titles (SOCOM and GTA 3 and Vice City, which happen to be the only games I own on this system), but while it does have more games, that leaves room for more crappy titles. I've always hated RPGs(Role Playing Games, not Rocket Propelled Grenades), lack of action on your part, more like a mutiple-choice test: Would you like to attack? Yes. Are you sure? Yes. MISS!!! Since I despise almost all RPGs in any shape or form, this takes away alot of appeal to own a PS2. Few titles are coming out that I am looking forward to. The new Syphon Filter looks awesome, can't wait. Not realistic, but a good action game where you pretty much shoot anything that isn't you. Largely run and gun.
The XBOX is more powerful, and creates shinier and faster graphics most of the time. Most of the time when a game is released for the PS2 and XBOX, the XBOX version has better graphics, smoother framerates, and quicker load times. The XBOX has 4 controller ports, meaning multiplayer is better. I don't have to pay $40 more to let my other buddies kill each other. The XBOX was designed with large-scale multiplayer in mind. I've had a 16 people, 4 XBOX Halo war go on for 16 hours straight. Halo is always great, team games really shine. Halo 2 will ensure that I will never have a girlfriend.
If sports games are your thing, I can't help you. Not sure which system has a bigger library of these. I've never been a big sports game fan, and every game I have either involves shooting or hitting people or aliens.