Aneimo

While neither really has much plot (obviously both being hentai) both have great girls and great sex scenes. The art of both has a similar style that is nice. Both are harems with one central girl, but the rest of the female cast is also exceptional. 

Similarities: - Hentai harems where there is one main love interest but the guy gets sidetracked along the way - High school students and the guy has known some of the girls for a long time Differences: - Harukoi Otome has sibling incest 

They are the same in a way that the lucky male protagonist is living with a harem of girls at home who are all very ''attracted'' to him. Both anime has high quality art and animation and bot of them are visual novel adaptations. 

Well, if you enjoy doing it with sisters, then I suggest you watch Anejiru... Let's just say, it has a more cuter story than Aneimo. But they're the same because they're both are "sister complex" based.