Gamecube all the way! My two favorite games, Wind Waker and Pikmin 2, are from Gamecube. The Wii U is looking like it could take my top spot with Pikmin 3 and a new Zelda.
Definitely the SNES. It had sooooo many good games. I think I'll name a few.
Super Mario World
Yoshi's Island
Final Fantasy IV
Final Fantasy V
Final Fantasy VI
Chrono Trigger
Secret of Mana
Illusion of Gaia
Donkey Kong Country
DK Country 2
DK Country 3
Super Metroid
Super Mario Kart
Kirby Superstar
Mega Man X
Mega Man X2
Mega Man X3
F-Zero
Street Fighter 2
Mega Man VII
Super Mario All-Stars
Mine is the N64. That's the one I grew up on the most and to me still has some of the best games to play for any console not even including the 2 Zelda games. Those 2 just make it even more genious.
It was close between the Nintendo 64 and the GameCube. The GameCube won out, even though the Nintendo 64 wins on the nostalgia front. Despite being Nintendo's "least successful" system, some of the best games of all time, in my opinion, are on the GameCube.
Nintendo 64 is my favorite Nintendo system. So many of its games were insta-hits, and basically form the groundwork for all games of this generation and maybe even next gens. Everything about the 5th generation in general was great.
Based on both nostalgia (admittedly) and just its sheer number of influential games, I'm goin' with the N64. Conker's Bad Fur Day, Banjo-Kazooie, Banjo-Tooie, OoT, Star Fox 64, Diddy Kong Racing, Super Mario 64, Mario Kart 64, Paper Mario, Super Smash Bros, Goldeneye, Perfect Dark -- great stuff.
I would have to say the Wii. There aren't many games I want from past systems that you can't download on the Wii, and I would definitely take the it over the Gamecube any day because you can play any game, use any controller, and use any memory card from the Gamecube, plus you can play Wii games. The reason I choose the Wii over handhelds is because I tend to like console games more than handheld games.
I'm going with the GameCube, just for the sheer volume of awesome games.Honestly, though, this is a really tough decision for me. There have been so many awesome Nintendo consoles (because they ARE the best), and I think all of them could be candidates for this (except of course for the Virtual Boy).
My favorite is actually probably the wii. But a lot of that is based on the fact it is backward compatable with the gamecube games, and a lot of titles from earlier systems are on the Wii store for purchase, so they are accessible as well.