Arakawa Under the Bridge, Nisemonogatari Recommendations
Both have the same Atmosphere,comedy and randomess.both male leads,Koyomi and Kou are practically the same and have to deal with weirdos around them plus they got the same Seiyuu.Arakawa uses aliens as the source while Monogatari series is using ghosts,vampires etc and both are by SHAFT
Both series employs the theme of word plays. Shaft is also the studio involved in both series.
Both series has many strange characters with strange personalities in a strange environment.
Both series also has a lot of drama, comedy, parody, and humor.
Produced by Shaft, these series tend to tell stories with extraordinary story-telling techniques, such as rapid screen cut, exaggerated facial expressions and body gestures, sudden focus on symbolic objects, and a heavy amount of inner monologue. Eminent Seiyuu, like Kamiya Hiroshi and Maaya Sakamoto etc, are also present in both series as main characters. Finally, the humor in both series are similar. Sharp-tongued sarcasm are to be expected.