I voted for EL&P (1st album). The list is really very good. Maybe, other albums made by Van Der Graaf Generator, Genesis with Peter Gabriel, Matching Mole (Robert Wyatt), Gong, could be included for the poll.
Anyway, I'm glad to read two basic albums by two important Italian groups as Premiata Forneria Marconi e Banco del Mutuo Soccorso.