Monster, Koukaku Kidoutai: Stand Alone Complex Recommendations
Both shows have really prominent elements of mystery and suspense which keep audiences actively watching and on the edge of their seats! Though one is obviously futuristic and the other set a few decades in the past they share a common allure due to the fact that they're so exciting and intriguing and they keep us guessing at things. They also both include a lot of ethical dilemmas. Generally, they're both just really awesome... :)
Both stories have short side stories, which are influencing the flow of the story and after a time the connection between everything gets clearer. The antagonist is in both stories very mysterious and the goals are unclear, they also have in common, that they are connected to each sidestory.
The animation style is the same. The same psychological roller-coaster is given to the viewer.