Lean because he made two of the best movies of all time. Bridge on the River Kwai and Lwarance of Arabia. Both of which I'd call the definition of epic and the latter still not quite being topped in scope without the aide of CGI. I'd also rank both of these abovce any of Kubrick's work.
I like Kubrick, I think he is overrated, but the man was a genius. Lean was better though.
Billy Wilder if for nothing more than Sunset Blvd. and The Apartment, though.