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Okay I misread the question; I listed mine based on visual appeal rather than "graphically impressive" so I'm gonna have to redo a few of my votes:
Wii: Jett Rocket; basically a tech demo for the Wii's ability to spam flashy multitexture shaders across every surface, and at 60fps to boot (Honourable mentions: Conduit 1 and 2, Metroid Other M and Prime 3, Mario Galaxy 1 & 2, Resident Evil Darkside Chronicles)
Wii U: Fast Racing Neo; a host of effects usually reserved for PS4/Xbox One games running at 60fps on a system far less capable (Honourable mentions: BOTW, Xenoblade Chronicles X)
Switch: Hard to say; games like Hellblade, Witcher 3, and Doom 2016 are the most impressive in terms of their rendering methods, but pay for it with low resolutions. Crysis Remastered strikes a pretty good balance and even had ray traced global illumination, though performance can be uneven. Mario Odyssey and FAST RMX do some great lighting and shading at 60fps.
