Depends on the genre of film (and I have a background in drama studies so that probably explains my opinions) but for me regarding modern cinema:
Dialogue - This is usually where you get the bulk of your character development and exposition unless you've got a corny narrator or some shyt. Hard for me to get into the plot of a film without this being solid. A good example would be the first scene of Reservoir Dogs.. That shyt set up the characters perfectly and I don't even love the film too much
Plot
Acting
Directing & Cinematography
Score & Sound
Edit -
It is interesting trying to rank this because what I like the most about a movie would end up just looking like a low-energy stage play, not cinema, if all the other elements weren't brought together well