5. Mega Man 5 (1992)
If the trilogy analogy holds up, Mega Man 5 fulfills the necessary duty of being the best of the bunch. Though it still carries over the simplified difficulty of the previous game, there are a lot of improvements made. Mega Man's charged shot has a much better animation, the colors in this game are eye-popping and all the robot masters feel fresh and new. There's a good number of catchy music tracks and some of the levels are the most inventive in the series up to that point. The gimmicky fun of Gravity Man's level and the gravity-less jumping in Star Man's level add a new dimension to clearing the stage. Plus, the story in this is easily the highlight of the game. Has Proto-Man turned evil? It's a great hook right from the intro screen. And his castle stages include the criminally underutilized Darkman, one of my favorite Mega Man baddies. If you're going to play one of the "easier" Mega Man games from the NES era, this is the one I'd recommend.