It's apples and oranges. Star Trek is true sci-fi: it takes philosophical and social ideas and translates them into a futuristic package, but the core is still the philosophy. Star Wars is action sci-fi. At it's core, it is an action story. They really appeal to different interests.
Furthermore, they've developed quite differently. The vast majority of the Star Wars universe at this point is fan-fiction: George Lucas retains little control over the phenomenon, and indeed the hardcore fans have actually written the newer trilogy out of existence and refuse to recognize it as lore. Star Trek's creators have kept somewhat tighter reins on the storylines and the characters in the various series. So as far as fan involvement, you're talking two totally different things.
If I have to pick, I guess I'm going with Trek.