Zoro is stronger, idk why but the concept of Zoro gets lost for many people.
Zoro's lvl is far higher than people think and sometimes lower than people think. Zoro is the bridge between Luffy and Sanji and what that means is it does not matter who of the 2 he is paird up with he will always perform on a simlar lvl. it does not matter if Luffy goes G5 when he fights together with Zoro, Zoro aswell will perform on G5 lvl. same when he fights the 2nd strongest oponenet when Sanji fights the 3rd (who is only slightly weaker) both will strugle the same both will look close to each other.
the difference between Zoro and Sanji is clear, when Sanji gets paired up with Luffy he will NEVER look as good as Luffy or even close to it. its always just clear as day Luffy>>Sanji. with Zoro that is obviously different when they paired up they are head to head doing many impressiv things 1 not better than the other.
thats why I never will agree with Sanji fans saying Luffy100, Zoro 90, Sanji89 statments. because what they doing is scaling Zoro of his Sanji side feats but not Zoro overall when he performed far better than him. so you basically ignore 1 half of Zoro Character and statments around him just to fit your agenda.
it will always be Luffy100, Zoro90, Sanji80