Probably covered, but why not? I've just bought a Wii U

[WhiteEaglePL]

I'm going to suggest a dozen, both physical & digital.
>Bayonetta 2 - bought it mostly for it too!!!! :D
>Donkey Kong Country Tropical Freeze
>Pikmin 3
>Super Mario Galaxy 1/2
>Metroid Prime Trilogy
>SteamWorld Dig (definitive version.)
>Rayman Legends
>Super Mario 3D World
>Super Smash Bros. U
>Wonderful 101
>Monster Hunter 3 Ultimate
>Hyrule Warriors

As for ones that are yet to release ; Starfox, Zelda U, Splatoon, Xenoblade Chronicles X.

W101, MH3, B2 & Pikmin 3 have demo's, so it's worth a try.