Gotta agree with those who mentioned Robert Johnson - "The Complete Recordings of Robert Johnson" are the primer for everything else.
Muddy is another great, no doubt, check out his "Folksinger" album, recorded live on a 'Delta plantation (for effect) and featuring a young buck guitarist named Buddy Guy.
On the topic of Buddy, check his "Stone Crazy" album. More recently (early 90's), check his "Damn Right I've Got the Blues".
And definitely the "John Mayall and The Bluesbreakers with Eric Clapton" aka "Beano" album rates way up there too. Hideaway and Steppin Out are classic. Also check out the DVD of the 1983 JM & Bluesbreakers with the Blues Greats show - Mick Taylor on guitar, Buddy Guy and Junior Wells, Albert King, etc. Also his 70th birthday show DVD with EC, Mick Taylor, and others is quite worthwhile.
The Stones are most definitely a blues-based band, and when they want to they can measure up with the finest ... their "Stripped" album is excellent in this regard, as well as their class live recording "Get Yer Ya Yas Out".
SRV deserves a mention, of course. When he and Jeff Beck toured together in '89 ... OMG !
Johnny Winter ... oh yeah, check out his album with Muddy called "It's Hard".
All the "Kings" - B.B., Freddie, and Albert.
As for LZ, they suck.