I don't have any of your coin choice girls except Cowslip Maid who i didn't build yet, but since i have both Maple and Kerria:
I've been looking at Cardamine Lyrata myself tho, and if i had coins i would get her in a heartbeat. I will rely on the rolls with the gems we get throughout the event and pray.

Kerria: Very good but very resource hungry. If she could marry skill activation she would, she also can keep herself alive in most content especially if they don't have the extra accuracy bullshit. But as i mentioned, don't even think of using her with less than 3 skill act girls or a turn one 1.65x/2x + one or two regular ones (Obviously less ideal if the fight last beyond turn one with this setup).

Maple: Just in general a good aoe nuker that is kinda selfish, but also has an above average skill activator and a single really strong attack booster for everyone letting you use her with other "selfish" girls like Kerria above. She is AMAZING at clearing the side pests letting your single target nukes go to town on the bosses.

Myself i would probably pick Maple considering the girls you allready have but both of them are great and whichever you get you will not regret it.