Organically Sanji was never meant to be Zoro's equal in combat, they often times compete like two siblings do trying to figure out who is "Better" but it was never about individual strength.
Sanji and Zoro have never had a fight, One Piece data books that are either reviewed or straight up written and even referred to in different SBSs have Zoro and Luffy being equal in combat and Sanji being a level behind.
Worst Generation is a generation that was meant to rule the new era and Sanji was not part of it, while Zoro was. Oda even went out of their way to have them actually fight and both wanting to know who is stronger where as in Zoro's mind it is clear that he is stronger than Sanji. And that stance is supported by both gag moments like Zoro saying he is worth 2000 men and serious moment like Zoro taking Luffy's pain and knocking Sanji out claiming it is warriors job to protect and not cook's.
Even recently among worst generation and new generation in general 5 people were separated facing two emperors, the gate keepers of current generation and those 5 people are Luffy, Zoro, Kidd, Law, Killer and Sanji is not one of them. Zoro is often compared to his captain by bystanders as well.
So even if you don't want to subscribe to feats which heavily favor Zoro, portrayal, hype, in universe statements and external source material all points to Zoro and Luffy being comparable in combat and not Zoro and Sanji. It almost diminishes Zoro's worth as a character if he is close to Sanji in combat.
