We currently don't have enough info to say, at least imo. I like Shanks a lot more and maybe that's the reason I might get a little biased but I think he edges out Mihawk. Again, the reasoning isn't concrete and it's just that Shanks' aura feels different. Like when Mihawk was in Marineford, people were giving respect to him and all but when Shanks entered, the reactions were just different and felt more powerful.
I personally don't agree with the one hand handicap argument though. I mean Zoro lost an eye and it has never been treated as a handicap. I would've agreed if it was his dominant hand but I don't think it's even that. Then again, Mihawk can always be proven as the stronger of the two currently if Oda feels like. We'll definitely get a confirmed answer at one point in the story. Till then, just let someone enjoy his headcanon, lol.
I personally don't agree with the one hand handicap argument though. I mean Zoro lost an eye and it has never been treated as a handicap. I would've agreed if it was his dominant hand but I don't think it's even that. Then again, Mihawk can always be proven as the stronger of the two currently if Oda feels like. We'll definitely get a confirmed answer at one point in the story. Till then, just let someone enjoy his headcanon, lol.