Duck Tales 1 & 2 for NES. After the Super Mario Bros. games, it's the best pure-platformer on the NES. Sublime controls, nice graphics that reflect the cartoon, great level-design, and some of the best music on the NES.
Pac-Man World 1 & 2 are really good, too. And I never hear anyone talk about them. I spent a lot of time on those games. Definitely not a traditional Pac-Man experiences, though, which is why I'm sure many people didn't like it. But if you can accept it as just a 3D platformer, then you'll have a blast with it.
Cool Spot on Sega Genesis and SNES was pretty good, too. Not as good as Sonic or Mario, but as still it's a surprisingly good platformer with some impressive graphics for the time; especially considering it's nothing more than a licensed-game based off a forgotten advertising mascot for 7-Up.