I don't read many published comics, so I have no idea. Webcomic wise, though? I guess everything about it?
My comic doesn't have any escapist or fantastical elements, it's a slice-of-life, character study type of psychological drama focusing on mental health, bad people and bad relationships. It has no romance and has some elements of horror due to one of the character's psychological state as well as later on events. It also deals with a lot of heavy subjects from abuse and trauma, to bigotry. None of my characters are reliable or competent in any way, and are assholes most of the time, intentionally and unintentionally.
I'm not trying to brag, someone told me on Twitter out of the 200+ comics they sifted through on a webcomic promo thread, mine was the only one that stood out and fit their interest, which was actually really flattering. Not gonna lie. (The person in question didn't want comics with any fantastical elements or romance.)
Another thing that sets it apart is that the comic is entirely traditional and in full color, while there are some comics like mine in that department (Lost Honey is a great traditionally example. Toilet Genie also has some pages in all watercolor), it is still really rare. Rare enough that there are some people who've told me that they won't read my comic because it's not polished enough, or that my comic would look better if it were drawn digitally.
My comic overall is extremely niche, making it not very palatable to a lot of people. But I have a very specific story I want to tell, and even though it will never get as many readers as other comics, I still very much enjoy working on it.
Edit: Eeeh I guess I should promote my comic since everyone else is using this as a promotion thread.