mei says hiSakura
But the usual idiots on NB will say otherwise
Kurotsuchi, Mei and Konan are all stronger than Sakura. I could even made a case for the last one being stronger than Tsunade.kaguya isn't ninja , she's from outer space and demon that's why she's out of list.
Top10 strongest female ninja
1) Tsunade
2) Sakura
3) konan
4) Chiyo
5) Mei
6) karatsuchi
7) Guren
8) Mito Uzumaki
9) shizune
10) Kurenai