If you're talking about great lead singers, my man jimmyt, I definitely disagree. I don't believe anyone could even graze Tony Williams of the Platters, and while the Flamingos were more known for their harmonies, their lead singers were really fine, too.
Guess it all boils down to a matter of taste.
And the lead singer of the Penguins had such emotion in his voice that while I wouldn't consider him the "greatest," their songs always pulled me in. (I will send you a whole, 16 track best of the Penguins CD, jimmy if you haven't heard their range of material.
And then, there was Sonny Till of the Orioles.
In a way, it would be foolish to compare someone like Sonny Till or Tony Williams to Johnny Maestro because their styles were so different, as were the songs that they recorded. They were all great, in their own way.
No need to determine who was the "greatest." They can't even agree whether Coke or Pepsi is..