It's so obvious that Oda is setting Zoro up to be his RHM, giving him CoC, having him stepping up everytime Luffy needs to make a hard decision or reassuring Luffy, the one who always trusts in Luffy and we've seen multiple times Luffy trusting Zoro's fighting abilities no matter who he is facing.
Stop it with the agenda already, Luffy likes every straw hats but not all of them are equals in power.
Luufy is the captain, then comes Zoro in term of leadership followed by Sanji.