I don't have many. Most of my favorite Wii U titles are Nintendo first-party well-knowns. But here's a handful that I really enjoyed:
-Captain Toad: Treasure Tracker - A nice mixture of platforming and puzzle gameplay with some very pretty graphics. It's nothing that's going to make your brain go mad, but it's just challenging enough to keep you going.
-DuckTales Remastered - It's the same, masterful game as the NES version, but better. Modern graphics, more story-details and dialogue, added content and levels, and a bunch of side-stuff and fan-service. Even without all of those bells and whistles, it's just a damn-fun platformer.
-Shovel Knight Adventure - Seriously, as silly as the title sounds, it's one of the best action-platformers I've ever played. So much fun. And underneath that slick design, there is some quirky humor, and a lot of fan-service to retro-gamers.