Me neither, to be honest, but if I had to say...
For underrated, definitely. Then again, this issue...
...is brought up. Funny how both were made by Clover.
So if I had to say an actually underrated game, I guess Breath of Fire III comes to mind. Some cool people like it, others say it's boring or whatever, but they're definitely (objectively) wrong. As for overrated, I guess I'll go with Musashi and say Ocarina of Time.