I would probably think the greatest was Hitchcock.
The guy who made “Gone With The Wind” also had a bunch of good ones.
Victor Fleming? He’s not really held up as any sort of all time great. He took over GWTW after another director was fired. And that director’s work was the better part of the film (the first hour or so).
Hitchcock has, to his credit, probably more films listed on “greatest films ever made” than anyone else. Seems like that qualifies him as greatest ever. I also throw Akira Kurosawa’s name into the discussion. His films are worth struggling over the subtitles.