Your favorite male soul voices

My favorites:   Marvin Gaye
                        Luther Vandross
                        Ronald Isley
He's considered a blues artist, but Taj Mahal has done some fine covers of soul and R&B tunes.
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There are some really good contemporary exemplars that deserves some attention. Check out Leon Bridges in his NPR Tiny desk concert. I'd also recommend Michael Kiwanuka and Charles Bradley. Gary Clarke jr is more blues-rock, but also worth a listen. 

+1 for Jackie Wilson. I saw him in my home town of Detroit when I was 
a kid or young teen. What an extraordinary entertainer he was. He danced and danced well all over his stage and could do full splits as well.