If I come across What If? issues in the $1 bin I normally pick them up.  Fun reading.

Thanks very much, everyone!

I've been a fan of What If since early in the book's run (#6 I think was my first issue and it's still a favorite comic) and still tend to get a little twinge of recognition each time I see one of those ideas replay itself. It was nice to finally list them all at once. I'm certain I missed a few along the way, especially of the secondary and back-up stories.

Francis, Samuel, good catches! I forgot about those.

I also probably ought to have said something about Volume 2, #105 becoming an entire comics line unto itself, but that was essentially the same creator spinning off his own story, so it initially didn't seem to fit the criteria. I'm still not entirely sure about where it fits into all this.

In any case, I'm glad to see that people liked it! Thanks, again!

Brian, issue 10 is also one of my favorites. Rick Hoberg was clearly at the top of his game on What If, and in that issue especially. In interviews, Rick and Dave Stevens have said that Dave assisted with the inks on occasional issues of What If. His hand is most clearly evident in issue 16, "What If Shang-Chi, Master of Kung Fu, fought on the side of Fu Manchu?" but I like to imagine I can see traces of his work in issue 10 as well. Whether Stevens was involved or not, there is some lovely artwork in that comic.

Other favorites of mine include: Issue 6 "What If the Fantastic Four had different super-powers?" Mandroid is still my favorite version of Johnny Storm.
Issue 12 "What If Rick Jones became the Hulk" No other issue encapsulates and brings the reader up to date on so many eras and storylines from Marvel history than this one, and it does so just by following Rick Jones through his life. Plus, the Teenage Hulk character is just plain fun... "Back off, soldiers! Unless you wanna RUMBLE!"
Issue 19 "What If Spider-Man had never become a crimefighter?" This one, and issue 22, perhaps best exemplify the book's central premise that the decisions we make on a moment-to-moment basis define the courses of our lives and the people we become. Peter Parker in this issue isn't evil necessarily, he's just... successful.
Issue 22 "What If Dr. Doom had become a hero?" Well, you just know this isn't going to turn out well... Really, just a great issue. The manner is which Doom's central flaw twists the events of his life is done exceptionally well, I think. Plus, its Mephisto is his prime.

There are other issues and stories I wouldn't want to have to go without in my collection: Issue 15, for the Walt Simonson illustrated adventure of the female Nova; Issue 17 the Villains issue; Issue 18 with the Tom Sutton illustrated Dr. Strange story.

I got into What If initially because each issue featured a brief explanation of how the events went in the Marvel Universe originally. Being primarily a DC fan all my young life, I enjoyed the ability to "catch up" on Marvel history with every issue. The intensely serialized nature on the Marvel books I'd read when I was younger had put me off the company. Marvel didn't seem to be able to actually tell a story. Everyone just ran around in place a lot, with everything left "to be continued next ish!" What If also afforded well-done, enjoyable Marvel epics in satisfying, done-in-one form.

Plus, the central premise was all about imagination and decision and the stories all about character and consequence. An unbeatable combination. Truly, one of my favorite titles.

I would have enjoyed the Byrne/ Claremont "What If Magneto had formed the X-Men" story JB describes in the book, "The Art of John Byrne." I pored over that section of the interview again and again as a youth. The sinister interpretation of Cyclops' visor was and is a favorite visual, and I'm certain that if the Wolverine-influenced version of the Beast with the claw devices had seen print, Hank as we know him would have forever after been drawn and imagined in that mold. Not that that's a good thing, mind you...

What If? #200 just came out a couple of weeks ago.   The numbering comes from using series 1 and 2 plus the various specials.  It features Stan Lee's first What If? story, "What If the Watcher Killed Galactus?".  There is also another story and a listing of all What If? stories along with the (very tiny) covers.  Roy Thomas is interviewed about how the series came to be.  In the beginning at least, Roy came up with the concepts and assigned them to various writers.