In any medium, romantic horror is my favorite!
I like reading Horror one-shots the most. Or things that are generally short. I don't have the long attention span or the patience to sit through 100+ chapters. Skip Beat is an exception, since I loved it as a kid. I think that there are plenty of hidden gems in oneshots.
I love Itou Junji, but more milder horrors that are just creepy are also OK. I read Kaoru Fujiwara's "Fetish" yesterday and it was really nice.
Other than that, I'll try to read any manga that looks gothic or has a distinct style.