Gantz, Claymore Recommendations
Both share semi-realism art style, gore and dark athmosphere.
High drama and not your typical protagonists make these series compelling. Both involve having super-human ability to take on alien/demon entities, as well as lots of action.
Shape-shifting creatures and a task-force of enhanced individuals tasked at taking these monstrosities down. Claymore differs being a medieval fantasy, with only shape-shifting creatures. While Gantz is a sci-fi set in modern times with a wide variety of grotesque monsters. So if your looking your a manga with a lot of action, monsters and gore I suggest you read one of these.