1. Mega Man 2 - Best Mega Man game and nearly everyone seems to know it (despite a few naysayers pushing MM3).
2. Link's Adventure - I could push this into overrated, but most people seem to know its pretty bad or at least among the worst in the series so I'm good with it.
3. Mario 3 - Great classic mario game. Well regarded. Seems about right.
4. Katamari Damacy - The praise isn't taken too far. No one is really saying this is among the greatest games of all times, but it's generally well regarded, as it should be.
5. Suikoden II - It's hard for me to say if this belongs here. This is generally regarded as the best Suikoden game and it is, so that's why I'm putting it here. I would say it's underated among games as a whole but at least it gets the proper respect within its series.