To be honest KIzaru only had a clash that lasted like 20 seconds in MF, they didn't fight during the whole war off screen (you can see Kizaru and Marco doing completely unrelated stuff). And Marco devil fruit is thus it takes time to defeat him. Heck, BM stopped fightning Marco saying she doesn't have the weapons to spare on him
Luffy:
- Beats Kata, a YC
- Beats Kaido, a Yonko
- Beats Blackbeard, a Yonko with 3 incredibly strong DF (theorized he also has a zoan)
- Beats Akainu, the Fleet Admiral
- Beats Im, King of the WG
- Beats Shanks, a Yonko (but whom I believe is more than a Yonko by "shonen" standards)
Order currently unknown for the last 4 if they are all Luffy's fights, just how I think they may go down.
This would signify that by default, Akainu is at least a more dangerous threat to Luffy post-Wano if they fight, more than likely due to his devil fruit and how lethal it actually is. This makes sense to me. It also works because we can assume Blackbeard/Shanks or Im, by virtue of this being a shonen, are also probably more dangerous to Luffy than Kaido was (assuming Im can fight and Luffy actually fights Shanks)
Then for Zoro:
- Beats King, a YC
- Beats Shiryu, another YC (but considered stronger than King for X reason)
- Beats Kizaru or Fuji (doesn't matter), Admirals
- Beats Monk Gorosei, one of the top world leaders (again like Im, assuming he's strong).
- Beats Mihawk, the WSS and equal to Shanks
In this way, you can sort of see why the YC<Admiral</~=Fleet Admiral~=Yonko mentality can work here. It IS complicated, because even beating Kaido before Akainu or Blackbeard by shonen logic means they are probably more dangerous/stronger than Kaido in other ways. Then you have Shanks, who's just a complete enigma but also an equal to Mihawk. It's a very complicated topic
No way to truly define the Gorosei/Im yet, all things considering. Even the SSG/CP-0 seem pretty dangerous too, but i dont think these will be direct strawhat fights unless Vegapunk gets his own arc with the SSG.
Not really one to powerscale, but this is how I view it because it's not an easy one to compare