I only like sci-fi if it's intelligent. And most are not... even the good ones. Being a sci-fi fan, I tend to over-analyze. But if there's enough action, drama or plot... well, if there's a good plot, I'll eat it up. Thus, movies like "Day After..." (pretentious, and ridiculous) and "Armageddon" just leave me cold, while I can still enjoy "Riddick" (no pretensions at serious science... just good old space-opera fun). But if it's too ridiculous an action movie, like "FnF", with poor research (SR20s in Integras? woooooo....), my brain kicks in and I stop enjoying the movie and start paying attention.
Basically, I like any movie that does NOT insult my brain. That includes intelligently or semi-intelligently written thrillers, dramas and the odd action movie that says "**** the brain, I want your balls."