Any recording from 1971-4, in my opinion and many others the absolute peak for the band. Many of these are available as Dick's Pick's as stated above. A personal favorite of mine is the recent release of a run of shows documenting the closing of the Fillmore East in 1971. It is a four disc set and the sound and music are both spectacular. Generally speaking you are lucky, there is so much good music out there, once you start exploring you may never stop!