Beatles - Revolver (1966) and Sgt. Pepper’s Lonely Hearts Club Band (1967)
Revolver was the first album where the Beatles took full bloom. They were great before this record, of course, but they were still mostly making poppy hits. The previous album, Rubber Soul, hinted that the band was likely capable of doing something new and innovative, but few expected the greatness of this record.
The Beatles used all the studio technology at their disposal and what was likely the best-selling art record of the mid-1960s. They weren't wanting to hold anyone's hand anymore. Instead, they were singing about depressives and more about the people they truly knew.
The band followed that with the concept album to change all concept albums. The tracklist is perfect and the second side plays as if it is one long, disjointed track. A song out of place might have wrecked the album only that each tune, from short to long, is crafted in a way that each note has an importance.
The Stooges - Fun House (1970) and Raw Power (1973)
The Stooges always had talent but their self-titled debut was a failure because they did not sound like the band did live. Instead of some pre-punk garage band, Iggy and his mates seemed to want to be a psychedelic band. That they were not. Thankfully, even after recording some of Fun House, the band, along with producer Don Gallucci, decided to strip everything out of the studio and record as if they were doing a concert.
The effect was that the band was much more in one's face and slightly dangerous. There was a bluesy-heavy rock feel.
Raw Power was a different animal. Produced by Iggy Pop and David Bowie, the mix was all wrong. The sound was too loud and unclear. The issue was that this gave the record a punk feel and hyper-aggression it otherwise would not have had. Songs such as "Your Pretty Face is Going to Hell" would have been completely different with overproduction. An accidental mix created the perfection this record remains.