I'm thinking most easily comparisons from one artist to another (J&MC to VU, Jan & Dean to the Beach Boys, etc.) or one album to an artist (The Final Cut to Roger Waters; Sonic Flower Groove to the Byrds, etc.). Reign in Blood sounds like Bathory's debut to me, as does Gorgoroth's Pentagram.
Lots of things have been compared to Sgt. Pepper's.
RADIOHEAD: THE NEW PINK FLOYD?