I think it's really like comparing Apples to Oranges (or for many Apples to actually GOOD x86 boxes ). There's two kinds of "space" movies really, "Science Fiction" and "Science Fantasy".
Star Trek doesn't follow a continuous story-line concept, but presents some interresting concepts and compelling characters. Trek also deals more with average every-day issues and sometimes political issues in terms of the over-all "moral to the story".
Basically with Trek one episode ends and another begins completely independent of that previous episode. Another thing that Trek tried/tries to "explain" is the technology used in the over-all concept. I'd say Styar Trek goes into the category of Science Fiction because of these observations.
With Star Wars every little nuance of the technology isn't completely explained to us. We still have these compelling characters, but we also have a continuity in the over-all story-line from Episode 1 through Episode 6. It's a simple story, but a very heart-felt one and one that touches on a more moral and personal level versus simply a political or technical explanation. To me, Star Wars falls into the category of Science Fantasy.
Most of my favorite movies have more of a "Science Fantasy" slant to them, like the Indiana Jones films, The Matrix, Tron, 12 Monkeys, A.I., 2001 A Space Odyssey, etc., etc., etc.
I guess this is why I've always loved Star Wars and simply "liked" Star Trek. Star Wars simply seems to have a deeper "meaning" to me.