KAMI NO KODOMO
This one is quite something. I would say to be mentally prepared before reading this cas it's real dark and fucked up.
Kuroshitsuji
If you like mystery, horror, or other creepy shit but you don't feel in the mood for something overwhelmingly dark then this is the story for you. This manga has an amazing balance between supernatural mysteries and comedy that make it possible for you to enjoy the story and binge all the chapters.
Blood-C
Watched the anime and the movie is one of my favorites of all time. The movie did a good job wrapping the loose ends of the anime
Blood+
Blood C (anime + movie) is better
Yakusoku no Neverland
I'm a HUGE fan of dystopias and horror and this manga is a disappointment. The plot is interesting but it is overshadowed by the extremely bland characters, and by a poor execution which is dialogue driven. The first 30+ chapters are just dialogues between the characters to make them seem smart. Although it's an adventure story, there is barely any adventure and it's mostly skipped or fast forwarded along with any possible character growth. By chapter 120+, only two real arcs have finished with 50ish background characters with no personality, a handful of "main characters" with 0 character growth, no real adventure arc, and a goal that is not quite clear to the reader. It makes you wonder how this manga is one of the current top 5 shounen. For a proper horror dystopia, see Psycho Pass. For a story with real good "what is going on" kind of Mystery, see From the New World. For a story full of adventure in a world against humanity, see 7 Seeds.
Tokyo Ghoul
My only issue is that the story writing can be very messy. It's hard to keep up with who's who
Visukiisu No Akai Ningyou