Never really thought about this. So much to choose from but off the top of my head,
Elton John - Not the strongest voice, but distinctive and great intonations.
Ewan McGregor - Not an established artist, but gorgeous voice in every song in Moulin Rouge. Of course Satine fell in love with him.
Ramin Karimloo - I wish i had a voice like his. Powerful and emotional. I adore his version of 'Till I Hear You Sing'.
John Mayer - one of the sexiest voices out there.
Freddie Mercury - Don't even have to explain.
Matt Belllamy of MUSE - Lots of range
Placido Domingo