Yamato Nadeshiko Shichihenge♥, Hana yori Dango Recommendations
Although the main female in HYD isn't gloomy like Sunako, both of them are strong and surrounded by four good-looking guys. Other characters are also alike in personalities and both are romances with some comedy. Both stories are really sweet and you'd probably enjoy them.
Both have reverse-harem, romance comedy. Both female leads are strong and the guys are the most popular people in school. And the characters Ranmaru Morii (YNSH) and Akira Mimasaka (HYD)are really similar too(both are playboys that have taste for older women). If you liked one you will possibly like the other.