For me the answer is easy: Mel Brooks. He directed movies in the sixties through to the mid-nineties, but he also directed my absolute favourite eighties movie, Spaceballs.
Although I don't actually like E.T., Indiana Jones, and other 80s films Spielberg directed, I can't deny how excellently well done they are, and how iconic Spielberg is as a director, so I would have to go for him.