I'd say Yukari, her boundary manipulation surpasses and counters Kaguya's eternity manipulation, the fact that she can turn the imaginary or illusionary into reality as shown during the Lunar Wars, the only thing that COULD stop Yukari is the powers of the Gods, while the Lunarians were said to be stronger than Regular Yokai, who the hell things Yukari is a regular Yokai, after all it has been said multiple times that Yukari poses a serious threat to the Lunarian Culture, Mind you these people effortlessly call upon the powers of Gods and foddered Remilia Scarlet and Sakuya Izayoi though it was said that Sakuya let her guard down and that was her undoing, Read the manga if you want more evidence for this. Yukari has been shown to have total mastery of her Boundary manipulation and Zero and Eternity happen to come under boundary manipulation, since Yukari not only has this but FAR more with boundary manipulation, it'd be foolish to think that she'd lose when she's got way better Hax, not only has she got better hax but is more versatile and almost likely that she's much older as Yukari's Boundary Manipulation can manipulate time and she has been shown to go through time before in the Manga. SO my Vote is Way with Yukari Yakumo
