BB King - Live at Cook County Jail. My father's favorite Blues Album
Everyone else has suggester many of the greats. You can get a good collection with a "Best of" collection from Chess Records. They had some killer musicians on that label.
Among those is also the great Big Mama Thornton. The pipes on that woman make me weak in the knees. After I heard her version of Hound Dog
I wanted to slap Elvis in the face for even trying.
Also damn the pay-radio. Just open a free Pandora account and start a channel with a few of those names or "Best of Chess Records" album, lean back and take in the goodness.