Wii U had a killer first-party lineup and great indie games. It's main problem, apart from the disastrous marketing and the fact it was visually too similar to the Wii (which made many people think it was just a tablet addon to the Wii), was it's underused gimmick with said tablet, which would have allowed for some very interesting games (still waiting for a tabletop RPG session program where the DM uses the tablet for instructions and storytelling while the party members only see their part on the TV screen, for instance), but sadly, there were not much efforts in that direction by either Nintendo, third party publishers or Indie developers.

I would give Xbox the gold, WiiU the silver, and Vita the bronze.

Xbox had a lot of great exclusive / launch exclusive games, from a lot of different genres — Halo, Halo 2, Fable, Jade Empire, Far Cry Instincts, Dead or Alive 3, Crimson Skies, Panzer Dragoon Orta, Ninja Gaiden, Knights of the Old Republic, Splinter Cell, etc. Plus it had an excellent lineup of PC ports: Doom 3, Morrowind, Half-Life 2, etc. Finally, it supported most of the high-profile third-party games of the period, and typically ran them better than the console competition.

OG xbox really deserves more love. Great games, hdd as standard, and a few other things.  Wii U had good games but was awful hardware.  The Xbox was pretty slick.

I have all three, yet the Vita is the only system I still regularly use.
Therefore, my vote goes to the Vita

I gotta go with the Xbox as well; the Wii U had some great games, but ultimately not that many of them. Xbox's library had considerably more breadth and depth.