Well, I'll just give a quick review for each of the Star Wars/ Star Trek movies I've seen:
Star Wars, ep. IV. Excellent.
Star Wars, ep. V. More excellent.
Star Wars, ep. VI. Excellent.
Star Wars, ep. I. Tripe.
Star Wars, ep. II. Serviceable, I guess.
Star Wars, ep. III. Really, really bad.
Star Trek. Interesting idea, boring delivery.
Star Trek II. Fun!
Star Trek III. It's kinda neat.
Star Trek IV. Very amusing, as intended. Well played, Leonard.
Star Trek V. Awful.
Star Trek VI. Good detective yarn.
Star Trek Generations. Dumb.
Star Trek First Contact. Cool!
Star Trek Nemesis. It was popular, but I hated it.
Star Trek (2009). Neato!
So, Star Trek turns out, all in all, to be a less ambitious series. Mostly, those movies used space as a platform for some other kind of movie. An uneven track-record for me, but more entertaining than not. Only two of the ten I've seen struck me as particularly bad, while five struck me as particularly good.
Star Wars, on the other hand. Well, I love the original trilogy. It is really excellent film-making. I like that one stormtrooper in ep. IV who bangs his head on the door-jamb. I also like everything else in all three movies, even the ewoks. A friend of mine can't stand the ewoks, but I like the fact that they're man-eating, war-faring savages. Yes, I love Star Wars. I insist on saying this, as I have since I can remember (born in 1977), which is why I don't consider episode I, II or III to be Star Wars movies. A real Star Wars movie has good writing, good acting, and a story that stays in line with its sister films. George Lucas wrote a spectacular "first book", and followed it decades later with a real clunker. I'm just going to pretend the prequels were never made. (But I guess episode II can stick around, what with Yoda flexing his muscles and that cool colosseum sequence, and the General Greivous and the hey-hey, glaven. But it has to be left as a weird relic from a series of movies that Lucas ended up never making, like a "lost episode" or something, seeing as how the first and third have been stricken from my record.)
So, I say that STAR WARS is a great and epic series. It's a real saga. STAR TREK is a much more modest affair. Of course, it has usually been modest on purpose. Character chemistry, plots in the tradition of the Twilight Zone and Alfred Hitchcock Presents. It's not an epic thing. It's a tv show, on the big screen. Like the X-Files movies. Just cool stories that play like extended tv-episodes.
So, I like STAR TREK better than STAR WARS. I like it better because it keeps going, it's usually good, and sometimes it's great. STAR WARS is bigger and more ambitious, but it's like the captain went berzerk and returned 20 years later to torpedo his old ship. What happened there?