I voted SNES because it is, in itself, my favorite system ever. Regardless of my feelings for SNES-era stuff, Nintendo themslves should be most proud of that machine. It was very custom and aside from the PCE it can kind of be said to be a forerunner of todays "everything is custom" system design. Virtually all the top games of the day where either SNES exclusive, or better on SNES.
Other reasons:
The sound chip is pure butter. Easily the best game related thing Sony will ever make

I would pay mad cash for a stand-alone keyboard with a SNES soundchip at its core.
The composite output is probably the best I've ever seen. Games like Tetris Attack and Final Fantasy VI just look wonderful.
The Famicom was more dominent, but honestly I never really cared for it. The arcade ports were almost all garbage (Ikari, Strider, WTF is this crap?) and while the MMCs made several impressive things spossible, they only seem to have been able to pull it off by making the system look like it was about to barf. I don't know how many NES brawlers I played where you could only seen the dudes' legs, or upper body, but never both at the same time. The NES's big strength was the pre-MMC stuff, IMO, like...Donky Kong, or Mario Bros. Not impressive, but at least solid and flicker-free.
The N64 blew chunks. Pace of good releases was about one a year through its whole life, and even most of those were loaded with fog. Most disapointing machine ever.
The Cube is like the N64, only not shit. Heavy emphasis on multi-player, which is good. A lot more original titles like Bomberman Land 2, Gundam (Pilots Locust, or whatever its called. I have it but I can't find it right now), Killer 7 (well, its Cube exclusive in Japan anway), Wind Waker. Also the GB Player is rad and there are more than enough Super f*cking Monkey Ball games, which I also love.
The Wii looks like it might be better than the Cube, but its hard to say.