Well, in my opinion, most definitely Wii. The Xbox Kinect has some rather odd technology linked to it that could be tied to something else... And, all of the games on the Kinect roster look either too boring or stupid to play, or not creative enough, along with the mix of extremely violent mind-numbing games.
With the Wii, you have the availability of an entire list of extremely creative and absolutely fun games, like Donkey Kong Country Returns & Super Mario Galaxy 2. So, in the end, the fun all boils down to the Wii. Happy Christmas shopping!