So it's been 2 years; which Wii U game makes the best use of the Gamepad?

[fleischr]

SURPRISE! It's an EA game : Need for Speed: Most Wanted U.

Solid Motion Controls with the Gamepad. Easy to navigate user interface. Actually useful 2nd screen functions.

Wind Waker HD was really great though too. The Wonderful 101 deserves a mention too, but it's UI is rather clunky.