If it includes future titles, it's not something we are going to know until the end of the generation. Else, it's just a matter of taste but, judging by what most people here seem to think, the WiiU is the better secondary even if its outlook seems bleak. I personally think that among the current three main consoles the WiiU is the least crap (primary or secondary). Impeccable timing, but seems most people are still too smart. Try again after the NX is properly announced.

If it wasn't for Zelda I would take XBO over Wii U as my secondary platform every day of the week.
Guess by the end of the gen I will be gaming on PC ,PS4, XBO, WiiU, 3DS, New 3DS and PSV
I only have the XBO left to buy after all.

At this point I would rather have an Xbox One as a secondary console to my PS4. I have a Wii U now but I have it for when my nephew comes over and for that it is useful. I never use it on my own. I am not interested in a single exclusive that has come out of Nintendo since Eternal Darkness and have little hope that will change. They obviously make quality games but they do not appeal to me.

I am not usually crazy about Xbox exclusives either but they will produce much more that will appeal to me over time than Nintendo will. Since I am not a Halo or Gears fan I can wait to purchase the console. Interested in Sunset Overdrive and possibly Quantum Break when it releases.

So for me definitely PS4+Xbox One.