Have you listened to them lately? Dude's voice goes flat and out of key in nearly every concert clip I've seen of him in the last 5-6 years. The guy can sing yes, but his voice definitely isn't what it used to be at all. The op never specified weather or not it needed to be current or past works. My
opinion stands on his present singing abilities.
I'm not saying I can do it either, but that's not what the op asked. If it was a requirement to be able to discuss the quality (which is all
opinion based, not fact as one mans beautiful sonata is another man's nail gun to the ear canal) of music we wouldn't have the need for a discussion forum would we? We would all be the same and no one would have a discussion would we?
And before you decide to swing your wide e-penis of your family's exploits in the choral world, I'm a music major to. I have heard both good and bad singers, and while my vocal practice is limited to concert and chamber choir's, I think I can hold my own
opinion. This isn't a bragging contest as your
opinion is your own, as is mine.