Vocals: Freddie Mercury (do I really need to explain?)
Guitar: Clapton/Santana/Hendrix - Three legends. Who can choose?
Maybe Clapton.

Again Im looking for the greatest overall musician . Not just the usual best on some instrument or singer.

Billy Joel also comes to mind. You must write the lyrics, music and play at least one instrument and sing to even start to qualify. So of those you mentioned Clapton certainly is the best according to that criteria.

Another would be Townsend.