Two of my very favorite rhythm and blues vocal group recordings are In The Still Of The Night by the Five Satins, and I Only Have Eyes For You by the Flamingos. Doug McClure was a teenager and sang tenor on In The Still Of The Night, which was recorded in a basement in New Haven, Connecticut, Where Doug still lives. Doug also sang for something like 17 years with the Flamingos. Fine as those groups were, that was all preparation for becoming the new tenor in The Gospel Messengers.
My other all-time favorite would be Earth Angel, by the Penguins. Doug assures me that he never sang with them, though.