Dorohedoro: Crazy series, never slows down. Fights tend to end quickly and brutally. More will happen in one episode than 4 or 5 episodes of another series. Just the first season is out. Seems to have a lot going on beneath the surface. You will notice a lot of little things on the second and third re-watch (little hints as to what is really going on).

Kokoro Connect: Highschool drama, but with complicated characters that have attracted the notice of... something. Some kind of entity that pushes them into interesting situations.

Re:Zero: Popular show about a guy who gets pulled into some sort of fantasy world. Don't want to give too much away. More complicated than it appears at first. The first season came out quite a while ago, and they are most of the way through the second season now.

Witch Hunter Robin: I don't really remember all the details (did this really come out almost 20 years ago?), but it was quite good.