Definitely Lauren is my first choice. She has a serious presence in her work, that makes you forget about the "girl" in Batgirl.
Nathalia is really an underrated actress. Her work in Wildflower separates her from the Olivia Holts and Bella Thornes of the world.
Despite her size, Audrey has this spunk and pluck, that could translate well to Affleck's Batman.
But for now, Lauren McCrostie can have the role.
https://en.wikipedia.org/wiki/Lauren_McCrostie
https://en.wikipedia.org/wiki/Nathalia_Ramos
https://en.wikipedia.org/wiki/Audrey_Whitby