I've been a fan of "Banco del Mutuo Soccorso" (wiki, official) for an indefinite number of years now. I hold for instance the view that their first three early '70s albums -- which I listen to frequently, on my iPod, e.g. while travelling from Chicago to Evanston and back--, Banco del Mutuo Soccorso, Darwin!, and respectively Io sono nato libero, are composed almost entirely of genius works, surprisingly underrated and little known outside intelligentsia circles (even in Italy). It is pretty hard to pin B.M.S.'s style down, or relate it to any other band's, since they combine uniquely various musical genres, rock, jazz, classical, all that plus the so Italian cantautore sort, in masterpieces that ought to rival in status and fame Pink Floyd's brightest creations.
Anyway, here is my number 1 choice: enjoy the superlative Il giardino del mago (very decent quality YouTube clip), from their first album-- with today's runner-up being Canto nomade per un prigionero politico, the major piece from Io sono nato libero.