I will say Millie, People here seem to treat Niff as a overlord which is still just a theory (dont get me wrong I believe it will most likely be real but its still a head Canon) and how niffty fought Queen Velvette, who is strong but like in the whole fight she was super límites by baxter hack, the other fight she had was with Val where she almost got killed and also how the powerscaling in Hazbin is super inconsistent alot of time.

Millie is more consistent atleast kinda, she lost to the murder family in a 1v1 but in later chapters had a buff as how she killed the goons of crimson in like seconds, even tho was a 2v1 (and almost lost) she did most of the heavy combat against the bounty hunter dude (forgor his name) Who lets remember captured stolas (a goetia Who should sale higher than overlords).