Director and camera. Makes me think of how Lucas wanted to make Star Wars very dark with lots of diffusion while DP Gilbert Taylor thought it should be bright and clean. After seeing the first dallies, the studio backed Taylor.
A Treasury of Rare and Weird Star Wars Posters From Around the World - The very first Star Wars poster by Brothers Hildebrandt, before the film was introduced. [I had this on my wall when the movie came out. I love this poster.
That's because Steven knew that with good editing it was a good story with amazing ideas. That's the thing about George Lucas - he's certainly a fantastic "idea maker," but not the greatest "storyteller.