As far as first party output, I really enjoyed the GameCube stuff they made, they had a nice balance of fun sequels (Smash Bros, Mario Kart, Mario, Paper Mario, Mario Party, Mario Tennis, etc.) and fresh new gameplay stuff (Luigi's Mansion, Pikmin, Chibi-Robo, Animal Crossing, Starfox Adventures, Kirby Air Ride, Donkey Konga, etc.)
SNES did have great games, but overall I just enjoyed GameCube more (especially since I played a ton of multiplayer GameCube stuff in the College Dorms). Third party stuff was great on SNES as well. And even GameCube got some great games from Sega and I played a ton of SSX Tricky as well.
I wasn't as big on NES as things were still rough game design/Gameplay wise in those days. You had to get good to overcome those challenges, yes, but it was a frustrating journey to get there, and when you did well, you were tense and focused... not really the relaxing and fun that I enjoy from gaming.
N64 was great for being novel at the time with 3D being new. But I prefer most the GameCube games to the N64 stuff nowadays. Still great if you like Collect-athon games a lot, and Blast Corps was really unique and fun.
Wii was novel, but waggle wore out its welcome by the end of 2008; still really great games on there if you stay away from the Everest of Shovelware that also muddied up the library. Not as great as GameCube, but I had a lot of great times with my friends (and even my family with the Wii).
Wii U I skipped. Gamepad was an instant no go, and I just did 3DS like most people. Switch is hoovering up the ports from its corpse so it all worked out for the best.
:D
Switch will probably surpass GameCube for me if the good games keep coming for many years. I prefer Nintendo Switch's form factor above any device I have used thus far, and there has been a nice bit of great games already on it.
I vote GameCube right now though.