Oh please, you guys have doubts... I don't... Jack Kirby.
Who was the second most prolific? Now that indeed is another matter... offhand, I'd also lean toward Kubert. But then bminor makes a good point with those Archie titles. They do look like they were drawn all those years by one person don't they?
Who was that, Dan DeCarlo?
And lets not forget John Severin, he had quite an output over the years.