Probably my favorite guitar player of all time -- maybe not the "best", but a favorite -- is Dickey Betts. His inimitable tone, his melodies, his technical prowess, his overall FEEL for the instrument has always floored me. I attributed much of his work to Duane Allman over the years -- ANOTHER favorite of mine, but for different reasons -- but I think back on the classic centerpiece solo from "Blue Sky" or the long fade-out jam of "Ramblin' Man" and I can't help but want to pop it in the stereo and get lost in his work.
1977's "Dickey Betts & Great Southern" is easily one of my favorite alltime albums, and one that I think gets lost in the discussion of great 70s albums. "Highway Call" is also a classic. Or heck so are the Allmans' "At Filmore East" and "Eat A Peach", although that's akin to making the observation that water is wet.