Depends on your definition of R&B--I think it's changed over the years. Do Sam & Dave fit it? Buddy Guy? Wilson Pickett?
Teddie pendigrass, isley brothers, keith sweat, mint condition, jagged edge, trey songs, chris brown, janet jackson, patti labelle,Anita baker, ciara, others
Luther, Chrisete Michelle, Freddie Jackson, One of my recent favorites is Share My Life by Kem.