Oda always does his best to keep Zoro and Luffy around the same level even after post-time skip. You just need to look at how even most of their power up parallel each other.
Base <====> 1 sword style
Gear 2 <====> 2 sword style
Gear 3 <====> 3 sword style
Gear 4 <====> King of hell style
- Gear 4 boundman <====> King of hell : three sword style
- Gear 4 snakeman <====> king of hell- three dragon swords
Gear 5 <====> Asura:dead man’s game
Gear 5 Barjung Gun <====> KoH Asura
FS <====> sleep diff CoO.
Nika fire manipulation <====>flame rant
Turn everything into rubber <====> BOAT (cut everything)
Coc coating <====> coc infusion
Internal destrution <====> CoA barrier
Overflowing CoA smoke <====> Overflowing CoA fire
Zoro's road to the top tier level is one of the cleanest so far. His wins and feats are unquestionable.
Leaving a scar on the WSC after a 1 vs 1 clash while on death door >> fighting a top tier and accomplishing nothing or with help. The only thing that can top that is to humiliate a top tier or beat them without help.
-Pushed back Fujitora with a nameless slash back in Dressrosa.
-Fought Kaido and Big Mom and countered their main arsenal, tornadoes, fire, homies, speed, and durability.
-stopped and tanked half of Hakkai
-Reopened Oden's scar and left his own on Kaido.
-Mid diffed a top commander like King who is the godfather of the seraphim that current emperor Luffy himself cant damage and who proved himself by beating another top commander in Marco. Unless Ben Beckman is a high top tier then King was the strongest top commander of the OG era. All while simultaneously taming Enma and surpassing Oden's swordsmanship with King of hell styles.
-Experienced double the damage from both Hakkai and damage accumulated from his king fight.
-As if it wasn't enough Faced death itself right after everything he went through