I have a PS3 and I've always had the PlayStations since PSOne came out. My roommate has all 3. The Wii is ok, the games aren't that great for it. Xbox has great games but most of them have hardware problems. He has sent his Xbox back on 3 different occasions to be fixed. PS3's are great for gaming and the BluRay player gives them an advantage in my opinion.
I might be a PS3 homer, but it's the best system out there right now.