"Star Wars: Episode IV: A New Hope" is the movie that started it all. With cutting edge special effects, a great storyline, and iconic heroes and villains this is the movie that sucked you in. You are a sucker for nostalgia, and few movies (if any) compares to the first time you saw Darth Vader. Without a doubt, "Star Wars: Episode IV: A New Hope" is your favorite movie.
(well I'd say ROTJ is really my favorite but oh well)