Warthur
Everyone knows that Queen were a fine live act... but god daaaaamn, were they amazing in their early years! Live at the Rainbow '74 captures not one but two complete shows (some truncated editions exist - ignore them), the first from the Queen II tour and the second from the Sheer Heart Attack tour.
As a London-based group, the Rainbow was something of a home turf for Queen, and the rapturous response they receive from the crowd is rewarded with a fine performance each night. I would actually give the Queen II set the edge - not only does it showcase just how much excellent material there is on the first two Queen albums, but it also seems a bit tighter. By the Sheer Heart Attack set they are already adapting to a different musical direction, and the somewhat longer set begins to flag.
Evidently, they were struggling to find a balance between keeping the set at a reasonable length and including everything they wanted to throw in there, a problem which would only become more acute as their parade of hits grew longer. The Night At the Opera setlist, as captured on the A Night At the Odeon live album, would be trimmed back appropriately; if you picked up that live set too then between that and this you'd have more or less the perfect sampling of live Queen from their early almost-prog/not-quite-metal days.