Last night I was listening to Bobby Darin sing "Moon River", he is best known for his swing style,but here he shows his talent.
I also played a Jack Jones CD. I was surprised how every song was just well done,hit material. Jack came by his voice honestly, his father was Alan Jones, also with a great voice.
I won't make a list but there are about 20, I think that I listen to regularly.
I always liked Goulet. You don't hear his music aired much anymore, but he had a fine voice. John Gary was another singer with a under appreciated voice.
The tittle indicates singular so I am going with Frank.
I know many will cringe at this one but, Ronnie James Dio had a fantastic voice in Heavy Metal, fantastic story teller and you could always understand/hear the words.