Still feel that Kaguya win, Madara was able to (roughly) keeps up with Gai, and there's nothing preventing Kaguya from BFRing him in a dimension. And while she was hurt by far weaker attacks than what Gai can dish out (Sakura's punches, unless you argue that she was low on chakra), immortality + lack of seal means that she might as well just stands there and takes his attacks.
And the usual overwhelming raw power. The 8th gate is all about that, and speed, and Kaguya is arguably superior in both.