I've been hearing that alot of people here believe that Kaguya is stronger than Momoshiki, I'm going to introduce three arguments, and here what you guys think about them.
1. People are saying that Momoshiki looks weak, well the Kage had 10 years for a threat they believed to be greater than Kaguya, so obviously they would be prepared for those two, however as shown in the manga they were not able to inflict any damage on Momoshiki unless Sasuke helped. Which just goes to show how strong he really is, even though the Kage were supposedly prepeared, some people would say that they were never shown training, but why would they just sit and hope for the best if they know what a Kaguya level threat can do. I say a decade because that is the amount of time Sasuke spent away from his family, and that's why Sarada never met him.
2. The second argument is that people do not realize how much stronger Naruto and Sasuke have gotten, Sasuke fully mastered his rinnegan, and Naruto got Kurama's other half, both are significant boosts to their power even though they were weakened prior to the fight.
3. Lastly why would Kaguya be afraid of people that she is capable of handling. She has abnormal powers, yet even with those she preferred to kill her children rather than stop building her army, to fight them. This amount of fear, requires them to be out of her control, she has many taijutsu attacks that she could have used, but instead she cowered and decided to kill her children instead of not building an army. How fearful she was of their arrival proves how strong they must be.
With that in mind, I believe that Momoshiki would win as even Kaguya, the pregenetor of chakra fears him, prior to Kinshiki's absorption, imagine after.