It's a hard choice, but probably the N64.
I feel like its games were the most different from anything that came before it.
- Super Mario 64 was the first time Mario was 3D (although Super Mario Sunshine is my favorite 3D Mario game).
- Goldeneye was the first huge console FPS, and multiplayer. We played the shit out of multiplayer.
- Star Fox 64 was super awesome. I especially liked that there were alternate paths to take.
- Perfect Dark had really cool gadgets.
- Donkey Kong was more than a platformer.
- Banjo-Kazooie. I still get frustrated that Nintendo didn't buy up the rights to all Rare games.
- Diddy Kong Racing.
- Duke Nukem.
Just too much stuff for me to list or think of right now.
Of course SNES and Gamecube both come close to taking the top spot for me as well. Heck, even NES could be a contender.
Wii, well, let's not talk about it too much. Nintendo really let the ball drop with it so far as I'm concerned.
Wii U has had too many droughts so far for it to be a contender for me. I go long amounts of time without having anything to play on it too often.