It's acceptable to debate the finer points of a movie and its value once its over, but it's a total waste of time arguing about anything movie night-related before the movie even starts. The majority of these fights seem to relate to what genre of movie to watch, who's in it, where to watch it, how graphic it is, and how long its running time is. The best means of avoiding stupid arguments about any of these things is to work out some sort of pre-arranged give-and-take schedule for movie night satisfaction (i.e. I get Jason Statham tonight, and you get Reese Witherspoon next movie night).
Sadly, you'll probably discover even this sort of agreed upon arrangement has flaws, and you'll still end up in a heated movie night argument about something totally inane.