In short those two do not deserve to stand out as the two "Best Looking" Wii U games. I think Zelda U, Smash, 3D World, Yoshi's Wooly World, Splatoon, Pikmin 3, ect all LOOK exceptionally well on the Wii U.

Saying that, I will say Xenoblade Chronicles X is by far the most ambitious Nintendo project to date.  it has the goal of being a vast, seemless open World shooting for 60fps. besides Zelda U, none of those other games can even begin to compete in the sheer computing work load it is going to put on the Wii U. With this and Zelda U we will basically see (granted there are always exceptions to the rule) exactly what the very limit of the Wii U is.

(I edited because I figure I should talk about Bayo 2 as well) As far as Bayo 2, I think there is a LOT of love from the developer to make the absolute best game they can for the next installment of Bayonetta. I think it has only helped them only being on one platform and they have optimized for it better than any other 3rd party game I have seen. Saying that it doesn't LOOK really any better than Pikmin, Wooly World, Smash, or 3D World. It has realistic textures, and that's about it. In fact, the last footage I seen the aliasing looks worse than all the others. Still it looks like a major painstaking labor of love project I can't wait to get my hands on. Bayo 1 looks the same. I would love to see some raw footage of it being played, and having all of the Bayoverse on a Nintendo console is awesome!

I reckon FAST Racing Neo might also be a strong contender in the Wii U graphics department. We haven't seen screens or footage yet, but Shin'en's pedigree speaks for itself, and the engine its built on its already showcasing some very impressive results in Art of Balance, with subsurface scattering, physically based shading, and 4k-8k textures.

Oh I can not WAIT to see those screens/gameplay, whatever. I've played Fast Racing on Wii and was blown away by how good that looked. Shin'en knows exactly what they are doing. That could very well be the best looking game on Wii U, we will have to wait and see. 

X hasn't impressed me, especially the faces. Bayonetta is very normal imo.. Still prefer games like Mario 3D World.

The new Zelda will surely trump all though, haven't been this impressed by a Nintendo's game visuals in a while :P

On a lot of the small things, the icing on the cake if you will, Xenoblade Chronicles X hasn't really impressed me either. What impresses my about that game is what it's trying to accomplish. Watching the treehouse, there were no frame drops (at least significantly enough to tell on a video that only plays a 60fps game at 30fps), the monsters were huge, the World was huge, the story is definitely there and very.... Monolith Soft for a lack of better term. It is a game that will succeed greatly at what it is aiming to succeed at. 

I do see the issues as well; the grass that seems to more bounce than flow in the wind, the textures that sometimes do not fully render, and the pop ins.

Then there's the moot point people always like to bring up, the faces. It's a design choice, not a flaw with the game. A lot of the vocal gaming community seems to take issue with the design choice, but saying a game doesn't look good because the faces aren't the way people want them designed is pointless and not really a valid arguement. They look like the original Xenoblade, and Xenosaga (granted rendered inHD). It's the way the people in the Xenoverse look, people really need to get over it. 

I think design is part of graphics, and to me a lot of the faces look bland. Don't think it's only a design choice I just think it's poorly presented.

Eh, if you say so. It boils down to opinion at this point.

No way. Xenoblade Chronicles X doesn't even looks as good as we thought it would initially. Bayonetta 2 looks good, but it's not that special.

I think Mario Kart 8 looks better than both, like Yoshi's new game and Splatoon.

Of allgames, Splatoon?
Sure, it looks fun, but it's no graphical showcase.