Sans the assumptions, the six names I immediately have are

Sam Cooke - Literally the prototypical male soul singer. Otis Redding - Literally the prototypical male soul showman. Stevie Wonder (LOC) - Songs In The Key Of Life is an album ... That is totally ignored along with anything from Stevie's classic period and it is pretty much (along with the next person I'm going to mention) the Revolver of Soul Music. Marvin Gaye (LOC) - What's Going On is the SGT. Pepper's Lonely Hearts Club to Songs In The Key of Life 's Revolver and, together, they are the apotheosis of soul music. Stevie and Marvin have birthed literally anyone that could be mentioned as a possible king of the genre. Brian McKnight - Brian is one of two people who could be King of Contemporary R&B and is one of the two who has as much raw talent as... Mr Golden Showers. I consider him Stevie Wonder lite as well as being his own artist. Joe - Joe has always been Marvin Gaye lite to me as well as being his own artist and his light light rivalry with Mr. Honey, I Married One Of My Protégés immediately puts him in this conversation and he is also the only other person who has as much raw talent as Mr. Step In The Name Of the Chicago Judicial System.

Dassit.