Among the main girls, which popstar is the least useful to you? Least useful as in inconsistent/terrible music, poor performance skills and vocals, basic looks and fashion, afraid to run her mouth (doesn't/rarely bring in the kiis and shade), etc etc.
All in all she's not important to your iTunes library and Google search. Having her around or not feels the same to you and you can't be bothered to interfere when you see her getting dragged by the media and stans alike, and you just kii instead.