Why is Qiqi recommended over Diona?

Hi, I have c1 Qiqi and c6 Diona, I’ve been using Diona with mizuki CMC and sucrose since the update. I think I just have to level cryo trav a bit more and farm the new set, but the dps is kinda low. Chalking it up to not having odette and my CMC being half built. That being said, is Qiqi really all that different from Diona in SSW granted I have Diona c6?

I know c6 Qiqi has like stellar quills or something but before that, what makes her stronger than Diona?