Sora no Otoshimono, Sakurasou no Pet na Kanojo Recommendations
The female main heroine of the series are both quiet, innocent, and their presence gives a somewhat similar atmosphere. Ecchi element is also can be taken as consideration, but sora no otoshimono is more direct than sakurasou.
Viewers can also experience a touching moment in both series.
The both anime gave the same atmosphere and both have some relationships problem. some scene are really funny and enjoyable and have more rarely a "dramatic" ambiance, the characters are interesting and unique. we can comparate shiina to ikarus, both are quiet and excentric and the main boy protagonist have to taking care of her.
Sora no otoshimono have more comedy than sakurasou, who have more drame than sora no otoshimono.