Specific subgenres unimportant, although having growled vocals is a bonus (I have discovered a weakness for ladies doing the metal growl), though a mix of growl and clean vocals is the best option.
Examples of female-fronted bands I dig:
The whole J-Pop/Metal crossover genre (eg: Babymetal)
Nightwish - girlfriend’s a big fan, and while I don’t dislike them, I wouldn’t seek them out.
Would rather poke my ears out:
In This Moment - her voice is the auditory equivalent of sinus congestion.
Feel free to throw in hard rock, though that’s not as hard to find.