Well mines are One ~Kagayaku Kisetsu e~, MOON. and Guilty _TheSiN_ (heavy incest) but MOON. is definitely most underrated imo cuz it has that edgy yet sweet romance (and some very stupid comedy). I kinda enjoy psychological horror with hidden badass characters xD.

I don't pay all that much attention to hype and all that, so I don't actually know how various VNs are rated.