It's subjective. Some people have education or a lot of experience with the art and technicalities of filmmaking, some people just like what they like without thinking about it too much.
Speaking for myself, I rate movies based on how much I enjoy them and how often I watch them again. Which puts Resident Evil and Jean-Claude Van Damme movies at the top of my list. Movies commonly cited as the greatest ever made (like Casablanca or whatever) don't interest me at all.