Clannad After Story was my favorite anime at some point as well. But then I watched a second anime.

My top 10 anime list changes a lot the more I think about it, but Toradora and Code Geass seem to pop up in it pretty consistently. Toradora for being one of my favorite romantic comedies, and for executing almost all of the themes I like seeing in the genre. Code Geass for its political suspense, crazy twists, and overall interesting concept. I guess I'm just a sucker for heavy emotions, which is the one commonality I'd note between the two.

Overall, I'd give it to Toradora, but both were amazing rides that I've found myself wanting to rewatch, which doesn't happen too often.

I want to watch Toradora already :(

I'm almost done with hell girl but i need to watch madoka magica next.

You should! It's fantastic!

I actually finally got around to watching Madoka recently...after being on the fence for a while. I'm a wuss when it comes to stuff like that, but I really liked it overall. My only advice it to watch it in as few sittings as possible, since the story has more impact that way. 

I don't watch horror, but closest thing was Monster and Ghost stories.

Monster

Elfen Lied

Tokyo Ghoul

Highschool of The Dead

Hellsing (it has vampires in it but no teenagers in it)

Deadman Wonderland

Parasyte The Maxim

Those are self defeating recommendations, are they not ?

Don't forget to watch the movies afterwards. The first two are well made recaps of the series and the 3rd is the continuation and end of the story.

Asking for horror anime with those restrictions is self-defeating too. What has too much action is subjective. i just recommeded good horror anime. 

Idk Deadman Wonderland and Hellsing seems pretty tame to me. I watched and enjoyed them, but I would not recommend them as horror.

This is coming from a guy who does not watch horror movies at all.