Some of my favorite records are collections of out-takes, b-sides, and other tracks that never quite made it onto albums. When carelessly curated (I'm looking at YOU, Anthology I, II, and III) they do little more gather cutting-room floor material for completists. But when assembled with care (or sometimes just luck) they can reveal something about an artist that their carefully-cultivated albums fail to. And since I haven't created a "Five Perfect" post in several years, I thought this would be a good time.
Honorable mentions: Black Market Clash, Still In Hollywood, side two of the cassette of Standing on a Beach, Give Me Convenience or Give Me Death, and Tom Waits' three-disc Orphans collection.