Stevie Ray Vaughan is the G.O.A.T. Change my mind
GOAT among the living? Billy Gibbons.
Those who have passed? Duane Allman.
And while I like the Top and the Allman Brothers, it's not that I'm particularly a Southern/blues rock/roots rock guy. I just think these are the two best. I do know this -- Eric Clapton brought Duane in to play slide. And Jimi had Billy open for him on tour.
JMHO.