If you consider them 'rock', I would have to say The Allman Brother's Band. Either the original lineup prior to Duane's passing, or the early 90's unit that included Warren Haynes and Allen Woody on the bass. They were superb, such outstanding musicianship! Not to mention the greatest white blues singer of all time, Gregg Allman.
Duane Allman, Dickie Betts, Warren Haynes & Derek Trucks are all universally recognized as some of the greatest guitar players of All-time, with Trucks and Allman always being near the top.