PlayStation? Wii? X-box?
So many choices…
Sega Dreamcast. Or an Apple Pippin if you can’t find a Dreamcast.
Seriously, though, it depends on the kind of games you want to play, and it’s a relatively bad time to buy right now, since new versions of both Xbox and PlayStation will be coming out before Christmas. (Or thereabouts; I haven’t been keeping close track.)
PS3
Good: Overall a very powerful, versatile, dependable system. Caters to a wide variety of tastes, something for (just about) everybody. Easy to shop for add-ons and upgrades when you need them. Free unlimited online registration (good for everything from ranking boards to chat).
Bad: Overall the most expensive system; peripherals, in particular, are almost ridiculously pricey, and I don’t even want to speculate how much the Move equipment will set you back. Overall the slowest system as well; some games have annoying load times, and expect LONG waits for system upgrades and almost all downloads.
XBox 360
Good: By far the best choice if you’re into fast-paced arcade action. Peripherals are (relatively) inexpensive and easy to come by. Has quite a few unconventional and niche games you can’t find anywhere else.
Bad: Games skew incredibly difficult. Something like Otomedius Excellent or Deathsmiles will tear your lungs out, and they’re on the lower end on the 360 scale. Need premium membership to get a lot of the good features. Probably the noisiest system ever; the constant gusting fans are something you’ll just have to get used to.
Wii
Good: A fantastic system if you love party games, shooting games, and analog controls.
Bad: A lousy system if you don’t love party games, shooting games, and analog controls. Uh…that’s pretty much it. And it’s the weakest.
Your call, sport. 
Isn’t there a price drop incoming for the PS3, or did that already happen?
The 360 and PS3 are so close to equal in terms of what hardware they offer, in practice, any choice should be made based on console exclusive games you want. You should be able to get either quite cheap, with a long, long backlog of great games to play. I have both.*
The Wii is a category of its’ own. If you’re a Nintendo (game) fan, you should get it. If not, borrow it from a friend to check a handful of great games off your bucket list. Since its’ already been superseded by the Wii U for the last year, I’m not sure how great their future release lineup is.
What titles and genres do you like? Do you do a lot of online gaming, and/or do you want to get “classics” of a certain type or platform from online stores?
How much do you want to spend ? How long can you wait ? What kind of games do you want ? The best platforms to get from a high quality/high performance standpoint are going to be PC or wait for the PS4. The cheapest is going to be Wii, which can be had for <$50 used on Cowboom.com and other places. But the Wii and Wii U are essentially 1 generation behind systems - Wii = Xbox/PS2, Wii U = Xbox 360/PS3 in terms of performance.
PC! 
Expect to see drops in the price of used PS3s and 360s after the new generations hit the market. If you’re planning on getting a current-gen system, this is probably the worst possible time to spend the money.