You can however weigh the strengths and weaknesses of each singer and categorically come up with an answer. For example, Geoff Tate's range far exceeds Rose's and Tate can sing more than two songs in a live setting without losing his voice. Axl is not in the running.
Nusrat Fateh Ali Khan mentioned once that a great singer must also have a pleasing timbre in his voice. That is also a quality that must be considered.
Tate is probably #2.
I do understand that Guns N' Roses is a favorite because they came into their own while a lot of people were discovering music. I just don't get the draw. Slash isn't a terrible player but he's not a guitar hero. I do admit he's above mediocre. However, I do not understand how Axl can be placed in a greatest singer category at all. his voice is more grating than great. He is a big personality, I do get that. That's his job, he does it well. The rest is absolutely quantifiable.
Quick Fact Check: False
Geoff Tate = 4 Octave Range
Axl Rose = 5 Octave Range
It’s not about my personal favorites (Axl is not my favorite) … if you are truly talking about the “best”, then you have to put aside feelings about favorites.
Range isn't the only parameter though.
Of course not, but it‘s certainly a measurable component of talent that you can’t merely sideline. Though, it’s not necessarily a measurable component when talking about favorites. Geoff Tate is a good example … most certainly one of the most talented singers, but not someone I personally enjoy listening to. King Diamond is another good example. Like I suggested before, these discussions are fun, but it’s difficult to put aside your own personal tastes. Hell, two of my favorites from back in the 80’s were DLR & Vince Neil … absolutely loved the both of them, but I’d never suggest they were the most talented. They both had voices that fit perfectly for what they were doing though. My own personal feeling is that it’s essentially impossible to pick the “best”, as that’s just going to vary from person to person based on what we all find personally pleasing. It always comes down to favorites in discussions like this (or best guitarist, burger, season, color, etc).
Winter is the best season, as I love to go skiing and ice fishing!
Spring is the best season, as I love watching nature come back to life after a dreary winter!
Summer is the best season, as I love to play outside and swim at the beach!
Fall is the best season, as I love the foliage!
I agree with what you're saying but we should be able to separate the 2.
For example, I know people like Yngwie or Vai have amazing ability but I can't stand their music. Most of the players I like couldn't even sweep the floor to save their lives, but I know they're not the best even though I prefer them over the widdly diddly sweepers.
Don't even get me started on King Diamond.