If you liked
Shinseiki Evangelion
|
...then you might like
Shingeki no Kyojin
|
Both are similar with a very dark tone and focus on the human condition. Attack on titan focus more on existentialism and ethics. It also is action heavy; the visuals alone make it a good watch. Whereas Evangelion focuses on mental illness and transhumanism. Evangelion tends to be lighter on action and violence. However it covers much more mature content and isn't far more disturbing.
If you liked
Psyren
|
...then you might like
Beelzebub
|
Beelzebub was done by one of the assistants who worked on Psyren. So they both have very similar art work and both give the same sort of feeling in their own different way.
If you liked
Soul Eater
|
...then you might like
Yumekui Merry
|
Both Yumekui Merry and Soul Eater have very similar art styles. They also have the same surreal aspect to them. I strongly believe that if you liked one that you'd like the other. Irrelevantly; their names are about eating certain aspects of the human psyche.