It’s a shonen and it often makes everything much more simple : Luffy is the MC, the best power is COC, Luffy is specialized in COC while for Zoro it’s COA, Shanks and Roger - straw hats bearers are hyped for their willpower, the story is like most shonen to have the willpower to surpass your enemy through and through etc etc.
you can bet Luffy have more willpower than Zoro
U would be right, if CoC was Best Power. Except that it's not
U think all that Luffy has is CoC? That's how he is gonna Save the World?
So Zoro's Power-Up to become WSS is CoC & Oda gonna repeat that with Luffy?
Sanji was trying to find his Emotions, Zoro is trying to find his Willpower
Next time we see Luffy, he is gonna discover something Greater than both, that's the Shonen Thing
Can't you see that Zoro have only his Right Eye while Sanji shows only his Left Eye?
Both are Luffy's Wings meaning that he relies on them both or what defines them?
Recent Chapters already debunked what you said, Zoro's PU to beat King isn't CoA, it's CoC combined with his New Sword
And Sanji's PU to beat Queen isn't CoO, it's retaining his Emotions combined with his New Body
Sanji have Fire that comes out from his "Emotions" & Zoro have King's Haki that comes out from his "Willpower"
Mark my words, Luffy's Next PU is gonna be Fire + CoC or in other words Emotions + Willpower
So i expect that Kaidou gonna make Luffy have an Emotional Crisis + Willpower Crisis (Combination of Zoro/Sanji Situation)
How can that be caused? Obviously with some kind of Death Situation
Sanji's Emotions burn hottest when he Protects
Zoro's Willpower takes over the most when he is facing Death
So Luffy's Situation will include him seeing Death & also Protecting someone
Since Luffy have Future Sight then he can see that Death without it actually happening
But it will be the Trigger for his Power Up, which is Fire King Form (Also known as Sun God Nika)