Sidonia no Kishi, Terra Formars Recommendations
They are both animes about a superior yet primitive race with terrifying powers who continue to evolve at an alarming rate, becoming more intelligent each step thus becoming a greater danger/terror for the humanity thought a select few who are "special" in ways take it up against these creatures.
They both contain some good ol' bloody gore and horror!
Both have futuristic settings and deal with a form of alien that becomes more intelligent. Sidonia has a much better plot, which more actual story, but still includes action and surprises.
Both series involve the human race being terrorized by another more dominate race.
Both series take place outside of earth in space on a another planet. The two MC's of both stories are very skilled and naturally talented but have lost love ones in the past and it impacts the way they deal with certain situations in the current time of the story. Both series are brutal and no one is safe especially the Main Characters, the narrative's have Action, Horror, Sci-Fi, and Space genre elements.
Both story focuses on the space.
Both anime has aliens that humans need to kill to survive.
Both shows are exciting and fast-paced.