I gotta go with Frank; at his peak there was no one close, imo.
Saw him live once: absolfookinlutely outstanding!

And, I've seen a lot of groups, individuals, etc. over the past
4 and half decades.

But, there may some "poll answer" that QwkAg pulled from
some site...

Edit... I sense Bob Hope, or Barry Manilow, or Wayne Newton or...