I've seen these guys live and was in awe:
Frank & Dweezil Zappa covering "Whipping Post" on the live release "Does Humour Belong in Music"?. Unreal. Still my favourite of all time. Frank was recognized more as a writer/composer than a guitarist, but believe you me (I saw him 8 times) he could play. I marvel at his genius.
Stevie Ray Vaughn covering VooDoo Child... to hell with it.... SRV playing anything! You don't just play the blues, you FEEL the blues! Saw him many times, most memorable was when he opened for the The Police's "Synchronicity" tour.
Eddie Van Halen: playing, doesn't matter what. The most natural guitar player ever. He was born to play guitar and has spent pretty well every waking hour re-inventing his skill and style. He really ought to play the blues IMHO.
Martin Barre from Jethro Tull: intense, and yet subtle chord changes that flow naturally. An artist with an artist's disposition.
Mark Knopfler: Yeah I know you see him as a rythym guitarist, he can wail in his own way. Day in and day out my favorite guitarist to listen to.