ok first of all for all the people spewing out ''prove it, prove it!'' ... the OP proved absolutely nothing and you can NOT prove your statement on this question because Luffy and Zoro have in fact never fought, there are feats yes but if you wanna go by those I would say they favour Luffy, even if not by all that much .... but there is no proof to say that Zoro i stronger overall, or stronger physically, if anything since Luffy's attacks are with bare hands he should be stronger
but here is my answer:
I have been a fan of OP for 10 years and in all that time nothing has ever made me think that Zoro might be stronger than Luffy, however I have gotten the feeling that Luffy is superior to Zoro time and time again ... it's up to you how much weight you want to put behind my statement
Zoro is not weak by any stretch of the imagination, nor is Luffy leagues above him
What do I mean by that ''feeling'' ... well ... Luffy is the main character, he will most likely be the pirate king, Luffy is Roger and Shanks, Zoro is Rayleigh and Mihawk (you know what I mean), Luffy is a D, he is the captain and Zoro his first mate, Luffy's father is Dragon and his grandfather is Dragon, ... well you get the general idea