As a reader myself, I look over the works I read, and a lot of the comics that have attracted me are from different genres. Action, Fantasy, Slice of Life, Romance.
But all of them have one key factor -- The plot's moving.
I like stories that have plot to them, not really stories that do mundane "let's sit around and do nothing until something happens" settings.
For example: Take @beta1042's comic "I Wish I Were You"
At the moment, the cast is at a paintball area playing a game. They're having fun, and it's kinda a double date. But, this is not a moment away from the plot -- it's a part of it. Because Chase has a slight moment of worry with his girlfriend Gwen and his friend Mason being alone. This is connected because throughout the story, we've seen Mason have feelings for Gwen, and Chase knows this. Mason's girlfriend Fi also knows this, but she trusts her friend Gwen and Mason to not do anything together.
That conversation between Chase and Fi goes back to the plot, shows character development and actions, and it keeps things moving. Something has happened.
That's what I attracts me to comics. If you deliver a plot, I need to see that plot in action. I don't want time wasted having all of the characters' backgrounds shown to me in the first chapter. Show that throughout the plot.