Millie, maybe? IIRC a fairly large percentage of her audience was female early on, but she never managed to attract more women over time, so she regressed to the mean. I think Enna also has a sizable female audience, she brings it up in a clip somewhere but I can't find it for the life of me (I want to say she talked about her demographics in a stream after coming back from Japan?). Neither one managed to capture the female audience's hearts in the same way that Vox gargling his own balls did though...
...You know, there are some regrettable conclusions about female-on-female vtubing in that chain of logic now that I think about it