I have nothing against Zoro as he is my second favorite character in one piece after Luffy, so if he does something great I cheer him and be happy. My problem here and those I response to here is those who belittle Luffy's haki comapred to Zoro without prove just to give him some superiority over Luffy.
Luffy so far proven himself and Zoro didn't. Anything else means nothing till proven otherwise including advanced haki usage in extreme battle which shows that it is indeed better than Luffy's haki.