Has anyone mentioned Guns n' Roses yet? Look, I won't dispute that Axl is the "bad boy frontman" of a lifetime and that he deserves all the credit for being a huge reason why GNR became so big.
But if you look at his vocals alone.... he's at cat ran over by a car levels.
Depends on what you're talking about in general. Live? Yeah, sounds like a banshee past its prime. In studio? Extremely strong vocal lines and raspy screams carried for many seconds, and a wide range - not just in octaves, but in delivery. When I was a dumb kid I thought Appetite had 3 lead singers. Now I'm a dumb adult, but I know better. He has some powerful live moments, but in general, yeah. Not the greatest.
I saw Ozzy live twice; once solo (that tour with Joe Holmes) and once with Sabbath (The End). The solo tour was one of the worst vocal performances I've ever heard. Everything you imagine to be bad about Ozzy. Whiny, cracked, flat, and "let me see your fucking hands!" after every verse. I saw him on The End tour in Mansfield, MA, and he was excellent. Human enough where you knew it was live, and it was detuned a shade, but it was solid, and that was a concert worthy of legends (didn't hurt that I was 10 feet from Geezer).
I saw Axl twice as well, once on the Use Your Illusion tour and once on the Chinese Democracy club tour (1,000 seater in Philly). He was great the first time; not perfect, it was live, but it was DANGEROUS, and so it fit perfectly. The second, I was truly blown away; the show started at 11:00 sharp, and I left at ten after two, and he was on the stage singing the entire time, save for Dizzy's solo spot and... one of the guitarists, I think it was Bumblefoot. So just about three hours. He sang EVERYTHING, and in tune and (I think anway) the original keys. Look, if you don't like his tone, you wouldn't have liked it, but it was GOOD (didn't hurt that the cute girl next to me was rubbing her butt against me the whole show while her hubby boyfriend sat at a table and surfed eBay on his phone. Dick didn't look up one time during the show while his wife danced away).