To choose 1 male singer as the best across all genres from the whole century is difficult. I really enjoy Joe Williams and Mel Torme for Jazz and Roberto Goyenetche for Tango. Frank Sinatra's album "September Of My Years" (on vinyl) get's me every time; not b/c his singing is so great but because his sentiment is so sincere, his song are choicees so elegant, and the orchestrations are impeccable.
