Let's talk about underrated games.
Rules:
1. Has to be something not well-known and loved, that is called underrated.
Example of bad pick: Zelda: Majora's Mask
2. Can't be a game with notable, major problems, that is irrationally liked by few
Example of bad pick: Sonic Lost World
I'll start. Marvel Land on Genesis, one of my favorite games on the console. Not a perfect platformer (jumping is floaty, pretty slow, repetitive albeit good tunes), but very solid, and has many well executed ideas. Prince Paco has some cool power-ups, such as the dragon wings. For example, all boss fights are mini-games, and warps are everywhere. Namco character cameos are abundant, and the theme park setting is great. Also a fantastic port, but with different enemies and level designs (and also 7 levels per stage instead of 4). I guess similar in this way to the Bravoman and Valkyrie ports.
Here is also an excellent shrine dedicated to the game.
http://marvelland.doublemole.com/