 If you liked
Boku wa Tomodachi ga Sukunai
|
 ...then you might like
Oniichan dakedo Ai sae Areba Kankeinai yo ne!
|
Similar comedy, artistic style, and characters.
Haganai is a bit more random and toned-down overall in terms of excitement, while OniAi is more exaggerated and focuses almost exlusively on the romance/harem aspect. Both involve plenty of fanservice (just watch their OPs to get a sense of it).