This one is kinda hard, it really depends on the comic. I guess my overall preference is:
1. Art: As shallow as it is visuals can really determine whether I'll stick with a comic or not, they don't have to be great but readable and expressive. I hate comics with really polished art where the characters look like robots void of emotion, when the artist has really great anatomy but never draw backgrounds, or where the they perfected a single body and face type but nothing else. All of those really take me out of a story, and are kind of jarring.
2. Characters: I like characters that are "human", who have flaws, make mistakes, argue, and react to situations differently. Those "pure", "role model" characters are kinda annoying. Everyone makes mistakes, we all treat someone like crap at some point, we can all be obnoxious. Let your character fuck up, and learn something from it, they will have more depth than if you don't! Flaws make a character more relatable.
3. Story: Put this last because as long as the story is entertaining to me I don't care how generic and stupid it is. Of course if a story is just bad with no entertainment value of any kind then I'll drop it. Also I'm really not cool with dark subjects like rape, abuse, etc. being shown as something that they're not. If an author lies to me about their comic being a "romance", I'll probably drop it.
Personally I don't really know what makes a technically "good" story either (just what I like), so I don't have much opinion on it.