My first choice would be a PC. Those can play anything and everything should you actually feel you need to. Granted a lot of that is illegal blah blah. In any case, after that, get a PS2 since Sony still supports it and still makes PS3 releases for it, or so I've noticed anyways. I'm not 100% sure on that. You'll be able to play any older PS1 or PS2 games and not gripe about backwards compatibility. then get an xBox 360 since a lot of the games you can play on it also come for the PS3 in the event you actually can't find a new release for the PS2.
But that's my personal recommendation anyways.