Oooh.... Wii U. As Fictionvision said, Bayonetta 2 and X look all sorts of awesome. On top of that, the new Sonic game is a Wii U exclusive, and they've got Mario Kart 8 on the way.
Out of the Xbone and PS4, there's no question: PS4. I've been laughing at the XBone since it was announced, and have gotten progressively more jolly every time Microsoft backtracked on some bullshit 'feature'. Whilst I have no illusions that Sony were likely going to do something similar had the XBone been better received, they at least had the smarts to change shit
before they announced it, and some of the videos putting the boot in were god damn hilarious (this one, for instance:
http://www.youtube.com/watch?v=kWSIFh8ICaA )
Plus, it's nearly a hundred quid cheaper, and doesn't have a pointless spy camera as standard.
One thing I will say, though, is the prices for PS4/Xbone/Wii U games are borderline hilarious (at least on Amazon). I realise this is the result of years of cheap living on the PC... but shit, son, £45 - £50 each? You'll forgive me if I wait until the prices drop/I can pop into my local used games shop whilst it still exists.