Genesis - Deep In The Motherlode
The album that marks the end of the golden age. If they had included "Duke's travels" (the very last prog gem from the plastic-sounding "Duke"), it would have been the perfect closure. Nevertheless, the sound of "A trick of the tail," "Wind and wuthering," and "And then..." deserves credit for creating the neo-prog of Pendragon and IQ (a genre that I love only thanks to Marillion, who are honestly a bit more than just a copy and paste).