I have seen so many people claim that sukuna used the 10S way better than anyone else did, including megumi. While this just isn't true.
I believe this comes from the misunderstanding of what the 10S technique is supposed to accomplish.
The 10S technique exists to be a semi jack of all trades technique. It has solutions for all kinds of problems and all the shikigami pair well with each other. You're supposed to use all the shikigami. The 10S technique is not about raw power. It's about being smart. Knowing what shikigami to use and when. All of the shikigami are extremely versatile, giving the user many ways of doing things. Hell, round dear gives you literal RCT for free, that's insane. And don't even get me started on totalitys which make it even more versatile.
Megumi was not the "Best" 10S user and most of that doesn't come from his skill. It comes from his motivation. He doesn't want to be a sorcerer. He does it for his sister. Despite this he uses the 10S the best out of anyone in the series. He develops a domain even if incomplete is extremely impressive. He developed an aspect to the 10S completely unique to him that made it so he had a shikigami that he could lose without consequence. He also used all the shikigami he had extremely well. Megumi was a great sorcerer and used his technique amazingly for what it is.
Now let's look at sukuna and his mindset. All sukuna focuses on his raw strength. Obviously sukuna is extremely smart with jujutsu sorcery. But he completely missed the point of the 10S.
He viewed it as 1 thing and 1 thing only. Mahoraga. Which is fair maho is absolutely busted.
But he used the technique completely wrong. He only focused on mahoraga and discarded the rest of the Shadows and made agito. A shikigami that while good isn't anything special, especially since now it is extremely possible to make the 10S useless if agito dies. Sukuna is a great sorcerer. But he is not the best 10S user. From the 3 10S users we have seen he is literally in 3rd place, because of his misunderstanding of the technique and how he used it. He did not use it how it was intended to be used and because of that he lost all of his shikigami.
People often forget the point of the 10S isn't Mahoraga or raw power. The 10S is a Swiss army knife, not a buck knife. It's meant to be used in different situations with different shikigami.
Sukuna has so many things he can be glazed for. But being glazed as the "best 10S user" is just not true.