Pink Floyd

The debut, dominated by the genius of Syd Barrett, and the subsequent "A Saucerful of Secrets" remain their masterpieces, two milestones of psychedelia, filled with nursery rhymes based on LSD and extraordinary cosmic journeys that would also inspire some of the great German bands of the '70s. After that, there was a slight decline, but until 1977 they consistently released excellent/good albums (Ummagumma, Atom, Meddle), and then the decline became more pronounced. Nevertheless, they are essential, and the Live at Pompei is immense.