I think we should only count games that were released for that hardware and not BC and ports right? Because otherwise I think Switch would blow up everything else
1) SNES: Pinnacle of 2D gaming, so many quality titles: A Link to The Past, Super Mario World, Donkey Kong Country trilogy, Star Fox, Final Fantasy VI, Super Metroid, Chrono Trigger, Megaman X, my favorite: Yoshi's Island!
2) Switch: WIP, but damn good library. Mario Oddysey, Splaton 2, FE Three Houses, Astral Chain, Breath of The Wild, Animal Crossing New Horizons, and that's just the exclusives there are very good 3rd parties too like DQ XI, Immortal Fenyx Rising, Octopath Travaler, etc
3) 3DS: Solid library too even if somewhat smaller, A Link Between Worlds, Yokai Watch 1 and 2, Pokemon Sun and Moon, Fire Emblem Awakening, Super Mario 3D Land, Kid Ikarus Uprising,
4) DS: Pokemon gen 4 and 5, plus remakes plus Mystery Dungeon (I really like most of Pokemon input from this era), Dragon Quest IX, Phantom Hourglass, The World Ends With You, Yu-Gi-Oh Nightmare Troubadour. I'm ruling out some SNES games I've only played from DS otherwise it would be higher
5) N64: Have some great games there are here, even if they haven't aged that well. Mario 64, two wonderful Zelda games, Star Fox 64, Pokemon Stadium 1/2, Yoshi's Story, Banjo Kazooie, Kirby 64, Pokemon Snap
6) Game Cube: Played mostly thanks to emulation, but here it goes: Wind Waker, Resident Evil 4 (I only know the PS2 version though), Metroid Prime, Resident Evil (game cube version)
7) Wii U: Has a surprisingly tiny but good exclusive library, BOTW, Pikmin 3, Tropical Freeze, Captain Toad...
8) NES: I don't really think their games aged sufficiently well to be played. I find original Final Fantasy ok-ish. I really do like Super Mario 3 though
9) Wii: Mario Galaxy, DK Country Returns and... err... Xenoblade I guess?
I don't know enough about GB/GBC, GBA or Wii U. I'm still ranking Wii U nevertheless because I've played some of its games on Switch. For GBA there is 3rd gen Pokemon and The Minish Cap