Personally i'd go with the PS3 as it had an extensive game library already and will still be supported for a few years into the PS4s lifetime, the new models are backwards compatible with PS1 games (but not PS2, but you can pick those up for a song anyway), the PSN is free if you don't get PS+ (which is a good service so far), which also gives you access to PS1 and PS2 games digitally. The PS3 also has quite a few great exclusive game and series; like inFAMOUS, Resistance, Ratchet and Clank, The Last of Us, Heavy Rain, Heavenly Sword, Uncharted, Metal Gear Solid, LittleBigPlanet etc. I could list more but then I'd have to google it. Also, with the PS3 coming towards the end of its life, the games and the consoles themselves are getting cheaper.
While the Wii-U might have a few games out now with a few scheduled, i'm still a bit dubious, the current games library is not that great (discounting Wii games) and while yes it's backwards compatible, there isn't that many great games that have been released for the Wii overall. That being said, the Wii-U has promise, but if you're going to be able to get both eventually, wait a little to get the Wii-U see what else comes out for it, by then it might also have dropped a little more in price as well.