NOTE: I posted this in a thread ("Who is Marvel's flagship female?") over on the Marvel forum section, but thought it might also be useful / interesting over here.

The numbers are based on Diamond's Top 500 Comics list for November 2018 using both Marvel and DC's female leads (to the best of my knowledge):
* 25th - CATWOMAN #5 (DC) - 50,131 copies
* 33rd - WONDER WOMAN #58 (DC) - 44,467 copies
* 45th - IRONHEART #1 (MARVEL) - 40,739 copies
* 49th - WONDER WOMAN #59 (DC) - 37,418 copies
* 53rd - BATGIRL #29 (DC) - 35,356 copies
* 56th - SPIDER-GWEN GHOST SPIDER #2 (MARVEL) - 32,715 copies
* 62nd - X-23 #6 (MARVEL) - 29,682 copies
* 66th - HARLEY QUINN #54 (DC) - 28,028 copies
* 68th - HARLEY QUINN #53 (DC) - 27,903 copies
* 80th - MARVEL TWO-IN-ONE #12 (with Invisible Woman - MARVEL) - 24,958 copies
* 89th - SPIDER-GIRLS #2 (MARVEL) - 23,189 copies
* 96th - SHURI #2 (MARVEL) - 21,881 copies
* 100th - SUPERGIRL #24 (DC) - 21,295 copies
* 102nd - DOMINO #8 (MARVEL) - 21,050 copies
* 105th - OLD LADY HARLEY #2 (DC) - 20,427 copies
* 107th - MR AND MRS X #5 (MARVEL) - 19,611 copies
* 123rd - SUICIDE SQUAD BLACK FILES #1 (Katana - DC) - 16,953 copies
* 138th - MARVELS CAPTAIN MARVEL PRELUDE #1 (MARVEL) - 13,316 copies
* 142nd - MS MARVEL #36 (MARVEL) - 12,827 copies
* 147th - PEARL #4 (DC) - 11,693 copies
* 155th - RAVEN DAUGHTER OF DARKNESS #10 (DC) - 11,070 copies
* 165th - SCARLET #4 (DC) - 10,405 copies
* 168th - SILENCER #11 (DC) - 10,018 copies
* 169th - HEX WIVES #2 (DC) - 9,869 copies
* 177th - UNSTOPPABLE WASP #2 (MARVEL) - 9,475 copies
* 189th - UNBEATABLE SQUIRREL GIRL #38 (MARVEL) - 8,298 copies
* 201st - MARVEL SUPER HERO ADVENTURES CAPTAIN MARVEL #1 (MARVEL) - 7,320 copies
* 213th - MOON GIRL & DEVIL DINOSAUR #37 (MARVEL) - 6,533 copies
Hopefully I didn't miss anybody. And remember, these numbers are based on what comic book shops ordered from Diamond, not necessarily how many copies individual readers bought.

NOTE: December 2018's numbers are also available, but some of DC's title featuring female leads didn't ship during the week of December 26th, instead being bumped to the following week, January 2nd of 2019.