I'll go with the first adult record I ever put on the turntable: Dark Side of the Moon. By far, it's the album I've purchased the most times in various forms…three times in the last year, even.

The 50th Anniversary edition (which has a 1974 concert on it) has a really cool "work in progress" cover.

b008fdb1-933d-847f-8162-18321cd31e85

variablepulserate.10centuries.org.