Kaguya or momoshiki. First off it was stated that momoshiki was far superior than kaguya in terms of rank and raw power however with that said, momoshiki had never even seen kaguya at full power-that being after she absorbed madara.
Momoshiki was easily getting boxed around by a fatigued naruto and sasuke and had to resort to absorbing the scientific ninja tool chakra for 1 last attack meanwhile kaguya was taking on full power naruto, full power sasuke, dms kakashi, and obitos kamui without even trying her hardest because she wanted their massive chakra reserves but to be fair naruto and sasuke weren’t at their true potential yet(and naruto only had half of kurama). On top of that the weakest version of kaguya fucked over isshiki in his own body using the element of surprise. Whether she had help from someone else or used a certain object is unknown
In terms of kaguya vs fused momoshiki, I think I’d have to give it to kaguya.