The final stage - from the runoff poll, we have five finalists
Raymond Chandler
Agatha Christie
Arthur Conan Doyle
Dorothy L. Sayers
Rex Stout
Who is the greatest mystery writer of all time? You decide. Poll to follow shortly…
I voted Agatha Christie…mostly because she’s my personal favorite. 
I voted Dorothy Sayers because I love Peter Wimsey and Harriet Vane. Both so exemplary and both so flawed.
Well put!
I almost voted for Agatha Christie, but I realized I liked her best three or four books, and the rest were very uneven. The last one I started, I didn’t even finish (which I’ve never done with a mystery before!). Because I realized the characters weren’t real enough for me to care about. And not only did I not care whodunnit, I didn’t even care what happened next.
Not a problem with Sayers (or Doyle or Francis or Chesterton or Stout or Marsh or Keane).
I claim the first vote for Chandler!
Rex Stout, who kept Nero Wolfe and Archie Goodwin going in style from the '30s to the '70s.
I voted Rex Stout, because he has by far the best tough guy name. And I like his books too.
Voted for Stout. If he had not appeared, probably would not have voted at all, as I do not really LIKE reading any of the other authors’ works, and I just couldn’t vote for someone as “greatest of all time” if I did not even like their work. I am wondering if others might not feel the same way.
I’ve never read any Sayers. I’ve read most of the other three’s books. I’m not a big fan of Christie, I find them a little to… sterile. I like Chandler a lot, but much of his work was so… grim. I suppose I like stout best because it’s, um, a little breezier in general, while still very clever.
Agatha Christie is by far the greatest in terms of overall popularity. Conan Doyle should take second place for his influence on the genre.
From Christie’s wikipedia page: “According to the Guinness Book of World Records, Christie is the best-selling writer of books of all time and, with William Shakespeare, the best-selling author of any kind. Only the Bible has sold more than her roughly four billion copies of novels.”
Four billion copies sold?! I suspect that few of the others have sold even 10 % of that.
Conan Doyle. Created the most fascinating and enduring character, with the cleverest problems to solve, set against the most intriguing and appealing backdrop, supported by the most stalwart and dependable sidekick. Holmes and Watson rule!
Rex Stout. Perfect period peices, dashes of humor, best characterization. And, the Police (or at least Inspector Cramer) aren’t fools.
And the asides about food and drink-simply amazing.
Right, the menus! 
I’ve voted for Chandler at every level here. But I think that what he was doing was quite different than what Doyle was doing. In Chandler, the whodunit is almost beside the point.
Conan Doyal is the one that hooked me on Mysteries.
I’m finding myself unable to vote. I love Chandler, and wish he had written more. I adore Stout, and was a nearly obsessive Wolfe fan when I was younger. I’ve enjoyed Doyle and appreciate his groundbreaking influence on the genre. I’ve enjoyed the bit of Christie that I’ve read, albeit to a lesser degree than the first three. I’ve never read Sayers, and since that is not the direction my tastes are going these days, I doubt that I will.
But for myself, I am not sure that there is a “Greatest Mystery Writer of all Time” that stands head and shoulders above the rest. Even if I added my personal favorites that didn’t make the list (PD James, Dashiell Hammett, Ross Macdonald, Robert B. Parker, Ed McBain) I probably still couldn’t vote for a winner.
I voted for Hammett in the earlier poll, but chose Doyle here.
I voted for Sayers because hers are the books that I have chosen to re-read the most often.
I voted for Doyle, because Sherlock Holmes is so iconic and influential and entertaining. (There’s a line from a TV commercial from several years ago that has stuck with me: in some context which I don’t remember, a woman says, “If I want a mystery, I’ll read Sherlock Holmes.” See: even a hundred years later, Holmes defines the genre.)
But I have no quarrel with anyone who selected Christie, Stout, or Sayers. From what I’ve read by and about him, I’d say Chandler may have been a great writer, and he may have been a mystery writer, but he wasn’t a great mystery writer.