Lots of excellent recommendations from others. I would also add Buddy Guy - Blues Singer and the great falsetto album Skip James - Blues from the Delta to go along with Muddy Water - Folk Singers stand out fidelity. It isn’t technically a blues album, but Van Morrison and John Lee Hooker - The Healing Game has excellent fidelity. There are so many others, but these are a couple that come to mind.
P.S there is often a wide range of fidelity quality on the same Howlin’ Wolf albums. There is an excellent high fidelity recording of Smokestack Lightnin’ on The Millennium Collection 20th Century Masters. The gain the engineer employed is quite low though.
So many great blues albums! I could go on for hours and write a book about it :).