Mario Kart 8 for me, althoughI'm expecting Bayonetta 2 to take the crown in October. Mario Kart 8 and Infamous Second Son are the two best looking games released this generation so far.

Mario Kart 8 and Super Mario 3D World.

But Yoshi's Woolly World, Bayonetta 2, Captain Toad: Treasure Tracker and Zelda U will all rival it or look flat out better. I've seen some extra polish on Captain Toad compared to SM3DW for example, nothing mindblowing, but it's especially noticable at the boss stage. That lava and light.

Pikmin 3 because MK8 seems, way ahead of the wii u compared to other games lol.

3D world

mario kart 8 just looks kinda pixely for some reason to me.
maybe its my tv idk but 3d world looks better to me.

Super Mario 3D World for it's consistency. Mario Kart 8 has some less than stellar models, Pikmin has some less than stellar textures and I just didn't find DKTF that interesting looking. Honourable mention to Trine 2 but it has the benefit of a fixed camera and a relatively zoomed out perspective to hide any potential imperfections.

donkey kong. U can see every follicle of hair on that damn monkey's head!

Mk8 followed by WWHD.
Zelda U is above all.

Probably 3D World.

3D World, MK8 and WWHD all have amazing graphics!  I am impressed by how Nintendo managed to improve Wind Waker's graphics so drastically!