I'd say definitely Michael Ball. He's got the most distinctive voice I've heard, very big and resonant. I tend to describe him as English musical theatre Elvis...
Also, Colm Wilkinson. If Sean Connery could sing and he was eating mashed potatoes at the time, that's who he'd sound like.
In my pants, she has burst like the music of angels, the light of the sun! --Marius Pantsmercy