Well, tastes differ, I personally couldn't care less for Sex Pistols or The Beatles or The Who or Deep Purple or The Rolling Stones (blasphemy, I know). They are not essential albums for me.

But I do have a lot of jazz, obscure Eastern European prog and German electronica.

(And I like 'Dummy', 'Mezzanine' and 'Wish You Were Here' enough to own physical copies).