It's all a matter of opinion. If you like those crappy, mature-rated, shooter games where you spend the entire game with guns shooting aliens or possibly other humans, then get an xbox. If you like childish, lesser graphics, with limited gameplay then get a Wii. If you like games that pull from both mature and childish games and create teen games with great storylines, then get a PS3.
Honestly, the only reason the Wii has outsold the other 2 is because of price. The PS3 is literally double the price. Plus, the new controls draw people in. People say "Wow, thats cool. Mommy, I want one of those". Then the mom sees the price tag compared to the other consoles and picks it up right there on the spot. It doesn't mean it is better, it means they have a better marketing strategy.
If you have to worry about price, then get whatever you can afford. They are games after all, you will have fun no matter what console you buy. But in my personal opinion, PS3 > 360 > Wii.