Right now, it seems to be Hara. But in future, I think it might be Jiyoung. Gyuri is the type of person who would take her career seriously so socializing wouldn't be much of a priority for her. Seungyeon did say that she wants to have a quiet job after the end of Kara, pretty self-explanatory. Similar thing can be said for Nicole since she likes to cook. Not too sure about Hara, but I think she will end up like Gyuri. For Jiyoung, being exposed in the spotlight at a very young age might have a big effect.