So, I have been recently started reading and rereading the original runs of Fantastic Four and Amazing Spider-Man. This has in part been spurred on by questions about the relative influence of Stan Lee and Jack Kirby upon comics, and who deserves the bulk of the credit for Stuff. Due to the existence of Spider-Man, Amazing Fantasy #15, and the fact that I can't really justify giving Steve Ditko much credit for the ideology underlying a character like Spider-Man ("With Great Power Comes Great Responsibility" is a sentiment diametrically opposed to the ethos of Objectivism), I have often in the past given Stan Lee a lot of the credit for the Marvel Universe, the Marvel Ethos, and a larger influence on comics in general. But, most people these days seem to give Kirby the bulk of credit for such things, perhaps in response to the undeniably shabbier treatment Kirby has received at the hand of Marvel and the general comics industry (Does Kirby's family see any more for the New Gods? I mean, one of these days Darkseid is going to be the major villain in a major motion picture. Why the Kirby estate see any money from that?).
Anyways, today I went on Wikipedia and added up some numbers. Keep in mind that I added up all of these number on a computer calculator, so there is a distinct possibility that I have some major errors in here.
For the total number of comic titles that Stan Lee has either a writer, plotter, or co-plotter credit, there are 946 entries listed on Wikipedia, by my addition. However, Strange Tales, Tales to Astonish, and Tales of Suspense usually ran two stories, and some of his credits for those titles were listed twice, so the actual number of individual issues involved is lower by a significant number, maybe as many as 100. Lee's only other listed credits are one thing for Simon and Shuster and the 15 comics for DC, 14 of which were just some BS hype thing called Just Imagine Stan Lee Creating where the conceit was Stan Lee created classic DC heroes based off of just the names. I remember those being pretty terrible and not counting for any sort of legacy.
Jack Kirby has 532 stories listed for Marvel Comics. Now, none of his stories for those three anthology stories listed above overlap. However, in each place he is listed as performing one of the stories, so giving him a credit for full title for each of those probably justifies giving Stan Lee double credits for when his anthology title credits overlap. But to be even, it's absolutely necessary to point out that drawing each of these titles was a much more time consuming process that writing them, especially given that this is the Marvel Method we are talking about. In addition to that, Jack has credits for 29 issues of Timely Comics, the work he did for what eventually became Marvel Comics, including the the work where he co-created Captain America. He also has credits on 284 comics from DC, and 113 comics from other publishers, resulting in a total comics credits of 958. Considering many of those titles are ones where he is either a co-plotter or full on writer, that really is just a staggering achievement in Comic Storytelling.
Also, the Wikipedia section on Characters Created By Stan Lee has 347 entries, and Characters Created by Jack Kirby has 316 entries. No idea how accurate either number is, or what even counts as a character here. So those number could be completely arbitrary.