h4xed my Wii U and it's kinda funny how much sharper 1080p versus 480p upscaled to 1080p is for old school games. Like...SNES, Genesis, etc. are so sharp on the Ouya, I had to use 25% scanlines on all the emulators just to kind of offset the clarity a little because my eyes were starting to bleed out of my skull, ha ha. The same games in WiiMode (or vWii as it's called) look sharp and clear but just enough to keep the graphics plain without any kind of eyestrain. I do kinda miss the scanlines, though. Guess instead of one emulator device on my TV, I'll just switch between the two depending on my mood. :p Wii U Pro support on the Ouya definitely is a plus.
Gotta say though, GBA.emu stomps VBAgx for all three handhelds (GB/C/A). The latter has a kind of warbly look which prevented me from using it much on the regular Wii, but the graphics scale perfectly on GBA.emu, and you can emulate all the GBC/A color options for regular GB (though maybe VBAgx has this feature as well). Sampled Aria of Sorrow and it looks gorgeous—25% scanlines to offset the low resolution (speaking strictly the gigantic pixel detail) and make it look a little more presentable on a 52".
MAME4droid is also totally boss and runs most games perfectly, though I gotta see how much further the MAME emus on Wii have gotten since last I tried several years back.