Kamisato Ayaka is a pretty straightforward DPS that deals most of her damage from her Burst. She has very high scalings on her Burst at the cost of it being 80 energy. You will likely need another Cryo battery on the team to provide energy for her (Diona, Kaeya, Rosaria, etc). She has a special dash (like Mona) and after she dashes, she will get a Cryo infusion on her Normal Attacks. Ensure you always have this bonus active to maximise your rotation damage.
Kamisato Ayaka's Charged Attack, Skill and Burst is able to hit enemies sucked inside Venti's Burst.
Her Burst also stays in place on frozen enemies and slightly knocks enemies away when they're not frozen.
Circlet main stat will be dependant on your overall stats, depending on your overall stats, one can be better than the other. Since Kamisato Ayaka is able to get a lot of Crit Value from (4) set, ascension passive, and also possibly weapons, ATK% circlets can be competitive to Crit ones, it also has a better drop rate, so don't throw away your good ATK% circlets.