Well like others have said because PS/Xbox share almost the same library and the exclusives are more similar to each other. With Wii U, not only is it cheaper but the exclusive titles are quite a bit different than what u find on the others.
With that said if Halo, Gears, Forza, etc. are more appealing to u than Mario, Zelda, Smash, etc. then get a X1 over Wii U.
When the herd loses its way, the shepard must kill the bull that leads them astray.