This is actually a lot harder than I thought and it changes a lot
Right now I'd say:
1. Beyoncé/Taylor - Taylor sells more but Beyoncé has more cultural impact, so I'd say they're even.
2. Rihanna - and it's only cause she hasn't put out an album in years. When she was releasing yearly I'd say she was more "popular" than Bey or Taylor.
3. Ari - she kinda has the twinks and gen z girls on lock, her singles/albums sell well - I don't think she moves the culture the way the first 3 do.
4. Nicki/Shakira - I think Nicki is more infamous at this point but theees no denying her impact and the sales (during her prime) were unheard of for a female rapper. She does drive conversation but not in a good way lol. Shakira is huge in Latin American but idk if she's like their Beyoncé or more like their Pink.