Music outlet, uDiscoverMusic has put together a list of vocalists that they feel are some of the very best, and Davey is one of them (Hell yes, he is.).
(Forgive me, I’m at work right now so this article is brief.)
See the link below to check it out!
Not sure about Heavy Metal…but yes…a million times yes…Davey is totally one of the best…if not best…vocalists of all time 
May Blag Dahlia and Johnny Rotten forgive me…but Davey is way beyond any level of awesomeness 
I think the idea here is his range. I didn’t have time to read the article line by line yet, since I’m at work but I wanted to put the article up.
uDiscoverMusic have like 20K followers and are verified on twitter. I made sure it was a reputable source before posting.
This list is terrible. They don’t even hit an actual “metal” vocalist until #4. There are so many other vocalists that deserve to be on this list before Amy Lee, Davey Havok, and Joan fucking Jett.
I don’t even listen to a lot of metal, but come on.