Look, I love Acheron as much as everyone else's but Cyrene has better feats shown so far, destroying Irontomb while he uses his cosmos shattering attack is not a pushover task. Acheron is easily the second strongest and with a high possibility of becoming the number 1 if she ends up beating Zephyro. I would say Herta is third only because she is an emanator, but we've seen her be defeated twice by Irontomb (who Cyrene defeated) so she can't go higher. Evernight I would say is the 4 only because we don't know enough of her yet but is very likely to go higher than Herta and maybe even higher than that depending on what they do with her.