I know that from the beginning here, the most underrated guitarist has been done to death.
So I am speaking more for under appreciated guitarists.
High accolades as far as contemporaries to them but grossly unmentioned.
My nominee for most under appreciated guitarist is Donald "Buck Dharma" Roeser of Blue Oyster Cult.

Great, inventive group in general that was around before the New York Dolls and Kiss.
Family men that had the appearance of union workers instead of glammed out pop metalists.
Heavy metal to me has always been more about the imagery in the music instead of the looks thing.
And Blue Oyster Cult had the musical imagary in spades.
The absolute Stephen King's of music.
Unfortunately overlooked because of the demon image.
They could rock as hard as any thrash band out there (and still can) and yet sound as soft and sweet as on any Kansas album.
And the guitar attack was definaly both a combination of axe grinding playing and classicalist performing.

The chic men with the leg warmers did more for the destruction of metal and rock in general and brought on the alt scene.
But acts like Blue Oyster Cult and later acts like Metallica, Iron Maiden, and Metal Church helped keep the respect in loud rock.

My hats off!

Matt

http://www.f3music.com/444