Usually these lists just turn into a list of everyone that everyone can think of.
Maybe the OP needs to do a tally?
For me, Freddie Mercury tops the list by far. He had it all. I'm not even a huge Queen fan so to me it isn't just about what I like.
It seems popular for some to dismiss Robert Plant (and Led Zep) these days. I think it is a reaction against all the hype that was (and still is to a degree) always behind the band that tried to make them more than what they really were. But in his day Plant had extraordinary range, primal power, willingness to stray into the bizarre and he had a very clear feel for the blues without trying simply to be a blues singer.
I think a more interesting take is the guys who don't have great voices, some who don't even have 'good' voices who are or were still epic singers. Think Geddy Lee. Even Bono to a certain extent. I love Mark Knopfler but he has almost no range at all. He always sounds the same.
