In Rolling Stone's 500 Greatest Albums of All Time, only 18 albums were live albums:
Live at the Apollo by James Brown (#25)
At Fillmore East by The Allman Brothers Band (#49)
At Folsom Prison by Johnny Cash (#88)
Live at the Regal by B. B. King (#141)
Alive! by Kiss (#158)
Live at Leeds by The Who (#169)
Happy Trails by Quicksilver Messenger Service (#189)
Wheels of Fire by Cream (#203)
Live/Dead by Grateful Dead (#241)
Kick Out the Jams by MC5 (#290)
MTV Unplugged in New York by Nirvana (#311)
Stop Making Sense by Talking Heads (#345)
At Newport 1960 by Muddy Waters (#348)
Rust Never Sleeps by Neil Young and Crazy Horse (#350)
Cheap Trick at Budokan by Cheap Trick (#430)
Live at the Harlem Square Club, 1963 by Sam Cooke (#435)
Live in Europe by Otis Redding (#466)
Live in Cook County Jail by B. B. King (#499)
for me, the "best" live albums don't merely replay studio tracks, but present new or dramatically re-worked material. this my own list would include live at fillmore east, quicksilver's happy trails and even stuff like joe jackson's big world and jackson browne's running on empty, all of which, i believe, are comprised of previously unreleased songs.