what are the most overlooked games in your opinion

I second Darkwing Duck for NES and Persona although I never played beyond the first one.

here are some I loved but rarely see anyone talk about:

SNES:
Axelay
Lagoon - a short and primitive RPG but the music was really catchy
Soul Blazer

PS1:
Alundra - at least in my area it was relatively unheard of
Armored Core series - the earlier games are probably not as overlooked as I think they are

Dreamcast:
Record of Lodoss War - if you wanted to play a Diablo clone