With my short attention span, I find it a challenge to sit through most movies .__. If I don't find it super-engaging, I'll probably doze off and start doing something else in the background, effectively understanding even less from the movie and making it even more boring for myself... orz
The most important thing for me are the characters. They don't need to be lovable, or even very complex, but I need to want to see what happens to them.
Other than that... Hm... I guess "beautiful world" would cover this one? I tend to enjoy the movies where I'd want to screenshot every single frame - because it's just so good - the most. So yeah, it needs to be visually captivating. Shot composition, set design, colors etc. all add up to this.
Contrived or overly cliched plots do detract from my enjoyment, but if the movie has one or both from the above, I might still like it. Also, the concept needs to be interesting to me to even make me watch it (there are entire genres I never watch for this reason). So... overall, my enjoyment depends on several factors?