The Allman Brothers. There isn't a better selection of music anywhere to be found in the last 50 years. Some of the band members are legends, others over the years are more obscure, but they have quite an assortment of elements that you can legitimately rank among the "best" in the business: blues/rock band, live album (
At Fillmore East 1971), slide guitarist (Duane Allman), blues vocalist (Gregg Allman), etc.
They are legends in rock music, with a distinctively American flavor (and a southern one at that!).
I have just acquired a couple of Allman Brothers Cd's that I did not know existed:
(1) Allman Brothers at A&R Studios where they played for WPLJ Radio in a Live Performance, August 26th, 1971, about two months before Duane Allman got killed in a car accident.
(2) Allman Brothers at Hollywood Bowl August 6th, 1972 along with Johnny Winter, this is before they got Chuck Leavell in the band.
I saw these on E-Bay and both were from England. They are great.