The Impressions - Greatest Hits (1965)

While it may have a been a bit early to issue a greatest hits album, you can't really argue with the quality of this mid-'60s anthology. It's no longer the package to obtain since MCA issued the excellent two-disc Mayfield anthology in 1992, and even ABC put out a good two-record vinyl set in the '70s. But as a single album venture, if you can find it, it's well worth getting.