It's a boring answer but for me it's Raiders Of The Lost Ark (the only Indiana Jones film that works).
If has the action, the energy and that spooky awe in the Ark scenes which match the Force scenes well.
It has Harrison Ford of course (playing a character very similar to Han Solo in the first two Star Wars films) but it also has amusing but believably nasty villains.
Karen Allen is as feisty and as attractive as the princess and John Williams doing the score for both helps.
Indeed Superman The Movie comes almost as close largely to the emotional sweep in the score (Margot Kidder and Karen Allen are almost playing the same role in the same way).
I always associate Close Encounters with Star Wars but that's more to do with me seeing it the following week (Star Wars was my second cinema experience and CE3K was my third).