Tbf Sanji does not have ACoA. What he does have is straight up stronger armanment hardening than Luffy and Zoro lol.
I am of the mindset that Sanji used ACoA to defeat Queen, and that while Zoro does have ACoA, he does NOT have Ryuo. Zoro openly commented on Luffy hitting Kaido with Red Roc and called it "the Haki he learned from that old man" (Hyo). I think Zoro was too stubborn to learn Ryuo from the Samurai...
Anyways, this really fits
Zoro, Sanji, and Luffy are all going to be masters of CoC
Since Luffy is the King of the Pirates, he'll have the strongest Conqueror's Haki.
Zoro will master the Offensive parts of Observation Haki and Armament, while Sanji masters the Defensive applications. IMO, Sanji will have stronger Defensive Armament and Future Sight, while Zoro will have stronger Offensive Armament and Observation Killing.
Sanji having Future Sight and Zoro having Observation Killing also balances them out, I think it works well.
I honestly want Shanks to just sit down when he shows up and tells each member of the Crew where their Haki and potential Haki is.