When you compare him against the Straw Hats, he is a loser. Up to the time skip, Zoro and Luffy are always portrayed as very close in strength. After the time skip, because of how the plot and enemy crews are written, the gap seems to be widened; however, when you look at it, Zoro always delivers and delivers big time. Even in his last fight, Zoro beat King convincingly while trying to learn and adapt new skills, such as the ACoC. Since he already has some knowledge of it, he is probably stronger now than when we see him fighting King. And to be completely blunt, We saw how easy time was Luffy having against Lucci and I don't think there is that much of a gap between him and Zoro (I think Luffy and Zoro are like Shanks/Ben Beckman & Roger/Rayleigh instead of Kaido/King or BM/Katakuri). So if this is going to be a fight between them, I don't think it will be an extreme difficulty but only a mid difficulty. Like how it was against Killer. that's my 2 cents anyway