I can't say who it "best." My favorites depend on the type of music. Van Morrison, Neil Young and Bob Dylan are perfect for their music. Of metal and hard rock, no one surpasses Ozzy and Plant for me. For prog, i love Peter Gabriel with '70s Genesis. For r&b, Otis Redding. For blues, the incomparable Howlin' Wolf. I think Captain Beefheart is amazing in his way (and owes a debt to Wolf). The "classic rockers" such as Lennon, Jagger, Janis, Hendrix and J. Morrison. I also love punk singers such as Joe Strummer, Johnny Rotten/Lydon and Joey Ramone.