I had a sudden urge to re-watch the original trilogy a few weeks ago. I'm sure MattG is responsible, or at least brought it to the surface.
George Lucas can, or at least could, assemble a rollicking good adventure. Plus, it's rare to see a sci-fi world that at least feels* coherent and lived-in, something that Star Trek only sometimes succeeded at. The world was a great deal more interesting than the main plot arc, to my mind. Han Solo's galaxy, with the smugglers, crime lords, and general scum and villainy, beat the pants off the usual science-fantasy trappings. (Perhaps the unusually high gun porn quotient** helps mask issues.) In fact, David Brin lays the smack down on Star Wars in an epic sort of way over at Salon (of all places). At the same time, he compares Trek favorably, which is worth some consideration.
* Read: Please ignore the fridge logic.
** A goodly number of prop-converted firearms were actual live (or at least blank-firing) weapons. Blanks are visible in several scenes if you look hard enough - the detention block break-out has a few, and you can see a few 7.62x25 Mauser cases flying when Han engages Darth Vader at the end of Empire Strikes Back. Supposedly, this was done so the art guys knew where to insert blaster effects, though they insert plenty elsewhere.