Hi,
It was always kinda raw and crazy, but that guy with Big Brother, screaming alongside JJ in "Ball and Chain" ... is something else. Likewise, in SF, that guy named Garcia, also left behind an incredible list of material with some really pretty guitar work, including slide.
Randy California (Spirit) also had some super nice stuff.
Robert Fripp, has some amazing tones, and I think sometimes his better ones are in other folk's albums. One Eno's first 2 albums, and even on Peter Hammill's "H to He" album. Some of the thunderous stuff in Eno's albums are really incredible.
SRV ... yeah ... he was special and then some, and probably the best guitarist I ever saw, although some would say that PF's Dave was better. I just find the flying and free-forming that SRV did, a lot more fun to listen to.
Ax Genrich, who did several albums with the early Guru Guru. Not only he had the tone, he also had the noise to go with it, and I'm not sure there was another guitarist that could do some of the crazy stunts that he did ... everything you ever wanted to do on a guitar that was not considered music, Ax did live on stage and in the albums.
Bill Nelson ... Be Bop Deluxe and solo. Some outstanding guitar stuff.
Toni McPhee/Groundhogs ... and I specially love "Crosscut Saw" and "Black Diamond". Two totally excellent albums. Beautiful sound all along.
Phil Manzanera, anyone?