I have PS3 and Wii. I never had a Xbox. Microsoft and Sony share pretty much all their game with this generation. There are some exclusives but nothing very noteworthy. I don't really the point to own a PS3 and Xbox 360 because of that.
Yes, I buy most of the systems that are out for the children in our home to use. We usually buy multiple versions just to make sure there's enough to go around, so having all three systems is pretty good for our setup.
I bought the PS3 because I liked all the features over the xbox360, about 2 years later I bought a 360 so I could play Halo, Fable and a couple over exclusives only. Later on I got the Wii mainly so I could play Updated Versions of older games (like smash bros original)
I used to own all three of the console, but my Wii was stolen about two years ago and I've never got around to replacing it as it wasn't that much fun to me to be perfectly honest. Right now, I only have the Xbox360, PS3 and the PS4.
Wow! When reading this thread I feel fortunate enough to have all three of these consoles I must thank my older brother. I have a Wii U, Xbox 360 , PlayStation 3, and a Wii. The funny thing about this is that I do not play any of these consoles and have become more and more a computer person but when I was dedicated to the PlayStation 3 or the Xbox 360 I was always playing with my friends, the type of person I am is that I only like a game depending if my friends have it and many of my friends have stopped playing games, so I rarely play unless I go onto the Xbox 360 or PlayStation 3 to play some classics because of their story mode or when many of my relatives are over and want to play a certain game on the console.