General Question I know, but I would like a few suggestions. I typically prefer more adult oriented horror/suspense anime, and I want something new (since I likely haven't seen it). Some of my favorites are:

Attack on Titan
Baccano!
Black Lagoon
Claymore
Code Geaus
Cowboy Bebop
Dragon Ball Z
Elfin Lied (Favorite)
FullMetal Alchemist
Ghost in the Shell
Mobile Suit Gundam Wing (Not a fan of the other Gundam series)

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I don't like over the top comedies like Kill la Kill and Tengen Toppa Gurren Lagann (But I loved High School of the Dead). I'm looking at starting Monster up, but it's a bit old. I'm also a fan of highly sexual anime, but only when the female characters have a strong role (like the Russian girl in Black Lagoon)

Thanks You, I appreciate the tips Try to name niche titles if you can

I know a ton of people will suggest mid to high tier anime but if you would like to see some underrated/hidden gem animes i suggest these as i enjoyed them. Only thing with some is i just wished they were 52+ episodes :-/

Anyway...

♥Symphogear: An anime thats definitely unique. Has alot of really good OST and the show kinda is focused around singing (but has a ton of battles). Its a personal favorite underrated of mine.

Pros.....
Epic Fights
Great OST
Heavy Female Focus (and its not ecchi thank god).

Cons......
Just 2 seasons waiting on the third (not really a con but...)
Season one has just one painfully annoying english dub episode. My god they cant speak english XD

★ Speed Grapher: Want a mature and wild anime? This has a pretty bizarre setting. Its about a photographer that stumbles onto an underground organisation that has rich/powerful people conduct crazy activities. (gambling,sex,etc) While there the protagonist accidently gets a virus (or something like that) from a girl which curses him of exploding anything he captures with his camera (Yes camera).

Monster
http://myanimelist.net/anime/19/Monster

Shiki
http://myanimelist.net/anime/7724/Shiki

Aldnoah Zero - Mecha, story goes to an interesting place.

Jormungand - Made by a lot of the Black Lagoon crew. Sexy femme-fatales abound.

Hellsing - Ultimate is more bombastic epic. The old series has better suspense elements. Both are worth watching.

Akame ga Kill - Fan service characters but also with a super dark underbelly in terms of plot.

Blade and Soul

First look says it's a cheap booby fantasy. It's actually a quite dark story with mature themes and a bit less clothing than is necessary.

Death Note - Cat and mouse murder mystery with supernatural elements.
Mushishi - Wanderer researching and solving mysteries revolving around mushi (spirit-like creatures).
Paranoia Agent - Creepy psychological mystery, I honestly don't know how to describe this one.
Fate/Stay Night - Great action and mythos.
Noein - Time travel, I can't remember a lot about this one other than I really enjoyed it.

Aldnoah Zero - Think the first arc is over, but this is one that will take you by surprise
Mahouka - Some great stuff here too (what the hell inda brother and sister shit is going on here???)
Broken Blade - Mechaction and deep, mature story... very mature story... only mech stuf that beats this is....
Knights of Sidonia - That no one has mentioned this is something I find shocking
Akame Ga Kill - This is a strange one, after every episode I keep telling myself it will be the last one I watch... keep coming back to it.

Kingdom
Tokyo Ghoul

Blast of tempest
Shinsekai yori
Fate/zero
Psycho pass

If you haven't heard, code geass have an ova series set between R1 and R2. You should check it out.
Even if you don't like gundam, gundam unicorn is an ova that's still worth a shot.

I've yet to watch but heard great things:
Aldnoah zero
Death note
Knights of sidonia

A bit hesitant to recommend but have to anyway (try at your own risk)
Steins gate

Suisei no gargantiaTiger & bunny

Anohana: The Flower We Saw That Day

Mahou shojo madoka

Sakurasou no pet na kanojo

Gantz
Akame ga kill
Psycho-Pass

I've really been out of the anime loop as I mostly read manga these days as I don't have much time and watch anime