Never bothered with The Moodies' debut. The hit didn't really do anything for me and it sounds like a completely different (and far less interesting) group so I never felt the need to hear it.
"Surrealistic Pillow" is such an obvious example I'm surprised I didn't think of it, especially w/ Balin's recent death. The debut is good in its own right but pretty unassuming. The sound is basically there (despite the lack of Grace) but the material ain't.
Always thought the Clapton album was Mayall's debut. That album and the other sessions w/ Clapton are really the only Mayall I'm interested in anyway (heard some of the later stuff but it doesn't do much for me)