I think its funny that People try to downplay Zoro, he is fighting Loki or Shonks just ask yourself the question who is his main fight when not one of them? the girl?
just comes down to who you think is stronger, when you think Shonks is stronger than Zoro fight Loki if you think Loki is stronger the other way around. both will be Top Tier tho, Zoro not fighting YC+ he is already one he needs to get stronger and not stay on his lvl. the progression path is simple, just like Luffy who did go from YC1 to Yonko lvl Zoro will do the same.