I would say it depends on the kinds of games you enjoy. If you'll play just about anything or expect both consoles to end up with about the same number of games you'd like, then I would wait and see what the PS4 has to offer before deciding. If the Wii U already has some games you want and you know Nintendo will make more along the same lines, then go with it. If none or very few of the current known Wii U games interest you, the PS4 might be the better option (unless even fewer of its known games interest you). Alternatively, you could look into getting a 3DS or Ouya (or both), though that would just add even more factors into the decision.
If you're on the fence I'd say wait. The PS4 isn't out yet and everything so far is just marketing and hype. When its out for a few months then gauge on what system appeals to you based on price, games, features etc. --- Gamefaqs: Where 14 year olds make fun of 13 year olds for acting like 12 year olds PSN: jacksonrr & Wiiu Nintendo Network ID: SonicKidd
Easy. Wii U. PS4 will take time to build up a decent library, Wii U is getting one this holiday. --- I am Lord Bowser, King of the Koopas! Bwahaha.. Playing Bowser on Mario Kart, and Noxus on Metroid Prime. I am not a cookie cutter!