What rank do you think he would hold?
Let's just presume here that Luffy followed in his grandfather's footsteps, never was a pirate, and never amassed the large bounty that he currently has. Let us presume that he never met Shanks, who inspired Luffy to become the Pirate King. Would it be realistic to think that Luffy could hold maybe an Admiral rank? Had he taken the Marine route… he may not have ever developed his Haki, or gear second or gear third. We should also pretend that Garp was in possession of the Gomu Gomu no Mi and Luffy ate it because he was angry at him.
I think, realistically, Luffy would be more than able to hold down a Commodore rank. That would leave him on par with Smoker.
What do you guys think?