Super Mario 3D World

Pikmin 3, followed by zelda ww :)

Super Mario 3D World.

Nintendoland probably second place, with Zelda Wind Waker HD in third. It's my least favorite 3D Zelda, but it's obviously still a good game. Nintendoland is probably the best mini-game collection ever made.

first party: donkey kong country tropical freeze
third party: zombiu

I feel weird saying this:

Lego City Undercover
The gamepad integration is the best of all the games I've played on the system with the possible exception of Zela WW.

Super Mario 3D World is definitely up there, but doesn't leverage the WiiU Gamepad enough to lift it above LCU.

Honorable mention to the indies...particularly Knytt's Underground. These guys are keeping my WiiU plugged in through the drought that the fickle 3rd parties have created.

Well, Wind Waker is my favorite game available for the console, but to make it easier I'll stick to games that originated on WiiU.

So, it's very close between 3D World, Tropical Freeze, and Pikmin 3.

Xenoblade Chronicles...and yes I'm serious.

Zombi U, 3D World, DK

Arkham City or DKC:TF

Mario Kart 8 obviously!