I think I've posted a few times before about games I'd like to see on Wii U and I'll go ahead again, more third-party, Pokemon Snap (a no-brainer, IMO, should be done before the end of the Wii U/3DS lifecycle unless they launch it with NX, if it retains use of the gamepad, I would think).
A Dungeons and Dragons-esque game where the gamepad user is the gamemaster and a few other players travel the world he is controlling, could take good advantage of local and online multiplayer.
A new IP that focuses more on a big story (with full voice-acting) in a post-apocalyptic world, with humans fighting aliens, a lot like Falling Skies, I think that could be a great title to launch with NX with good marketing.