For consoles, I'd definitely say the N64, by far. There was so many great games I have fond memories of.
For a game though, this might sound a bit strange, since it's still probably considered kind of new-ish. Super Mario Galaxy. I have the best memories playing through that game, it was one of the most magical gaming experiences I've ever had.
It looks really wonderful, you can see more about it on the Kickstarter page: Buddy & Me
The game was originally going to be for the iPhone/Pad and Android devices, but they've added the Wii U as a stretch goal. Unfortunately, it looking very likely it won't make it at the moment, with just seven days left. Either way, I thought I'd let people here know about it and see what your thoughts are on it. Plus I just wanted to share it, I want it so badly, I'd love it to meet its goal. ;_;