Jimi Hendrix.
For reasons, go read a copy of Crosstown Traffic, it explains it all. He basically took the blues to new places & at the time of his death left a gauntlet lying on the ground that no one has picked up since. He could wring so much emotion from his instrument, innovated in so many ways, he just played from the soul. Ever hear people cover his songs? They just sound two dimensional in comparison. I don't think anyone one will remember Steve Vai & his ilk long after they are gone, do you?
Blind Willie Johnson (slide player) & Robert Johnston also deserve a mention. Again, maybe not technically amazing but emotionally in a league of their own. Dark was the night by Blind Willie Johnson is one of the spookiest pieces of guitar I have ever heard & not an amp or effects pedal in sight.