NES

It's more impressive to invent the wheel than to perfect it. NES.

How dare you not let me troll vote the Wii U.

NES and SNES are really the consoles that established the foundations (and even cornerstones) of most of Nintendo's long-list of franchises.

The NES, of course.

Toss up between the Snes and N64.. does Rare count since they were own by Nintendo at those times?

NES is objectively the correct answer.

If we're arguing about runner ups, I can think of good arguments for 4 platforms: the SNES, N64, Game Boy, and Wii.

SNES - Deserves a lot of credit for series like F-Zero, Pilotwings, Star Fox, Yoshi's Island, Mario Kart, Donkey Kong Country, etc. I don't need to sing praises for these games and their successors. The problem is that some of these series would leave a rather mixed legacy. Sure, Yoshi's Island is great, but since we're talking about IP's as a whole, we have to admit that Yoshi games in general have had at least as many duds as hits. Same applies to Star Fox, which has only ever had two really outstanding games. Other series, like F-Zero and Donkey Kong Country, have had long periods of dormancy. I have to take points off for this sort of thing.

N64 - If spinoffs can be counted, the N64 deserves a spot. Mario Golf, Mario Party, and Paper Mario all deserve mentions (Tennis was on Virtual Boy). And there is also Sin & Punishment and Custom Robo, though the real stars are Super Smash Bros and Animal Crossing Forest. However, the same complaints I made about certain SNES series applies here as well. The only series listed above that have been both regular series and fairly consistent in terms of quality are Super Smash Bros, Animal Crossing, and arguably Paper Mario.

Game Boy - This is the home of Kirby, Pokemon, and Wario. It also gets partial credit for Dr Mario. Frankly, these are a solid collection of franchises. The thing is, the Game Boy was around for over a decade, including the Game Boy Color, and I could only think of four notable new series. There were plenty of one off games, but has anyone ever demanded a SolarStriker sequel? So this is roughly the opposite problem that the SNES had.

Wii - Wii Sports, Wii Fit, Endless Ocean, Art Style, Xenoblade... its not a bad collection, especially since these IPs often haven't had time to either be embraced or forgotten by history. Though Wii Sports is never going to be forgotten, and Xenoblade is an ongoing series, so who knows? Really, the Wii is the most notable 21st century platform in this debate.

Legend of Zelda is my jam, so NES for me.

Yeah, I'd say the NES, since it debut some of Nintendo's biggest IPs, one of my all time favorites Fire Emblem being one of them. The 2nd best would probably be the Gameboy, with Pokemon still being a massively popular and beloved series, and Kirby's an important Nintendo icon as well.

NES without a doubt! you forgot Chibi!