I don't wanna turn your thread into a Mihawk debate but bear with me for a moment here.
If you think Mihawk is Roger level then could you see the following scenarios playing out in you're head:
1. Roger gets his attack deflected by Jozu
2. Roger goes at pre skip Luffy with intent to kill but fails
3. Roger gets blocked and stalled by Vista for a while
4. Roger gets stopped by and clashes with Crocodile
Now, just so we're clear, I'm not saying that if Mihawk wanted to he couldn't wipe the floor with evryone I just named. He absolutely could. But is it not manga fact that all those scenarios I mentioned happened to Mihawk at Marineford? Could you honestly picture Gol. D fucking Roger, the guy that low diffed Kaido level Oden, in these scenarios?
On the topic of Mihawk being Zoro's final opponent, I don't think that alone warrants him being stronger than roger. If Zoro is to Luffy what Rayleigh is to Roger then there's no basis that EOS Zoro would be stronger than Prime Roger. Not saying it won't happen, I'm saying there's no real basis as of yet.
I think its more of a game of personalities at least that seems to be consistent in One Piece based on combat showings of different combatants.
One glaring example is Rookie Kozuki Oden vs Prime Whitebeard where they seemingly were presented as too combatant on equal standing. Worth noting their clash even had some intensity to it.
But then we saw Gol D Roger whose personality is not that of someone who pulls a lot of punches absolutely humiliated Rookie Kozuki in a single attack and the impact of said attack launched Oden a good distance. Granted Oden was durable enough to tank the said attack without any real visible damage.
Now if we were to give Roger Mihawk's personality of not hunting Rabbits with Cannons, meaning not overexerting one self when overexertion if not required, lets see how the scenarios you presented play out.
1.I think it was heavily implied that diamond is the hardest element a swordsman can master to cut perhaps even harder than cutting sea prism stone. And here we have Hawk Eye testing waters against Shirohige New Gate by sending a semi casual nameless flying slash that gets weaker with distance from across the island to perhaps invite him to a fight, got stopped by Yonko's 2nd or 3rd commander with a fruit that is anti swordsmanship with a great deal of struggle and still end up in few bruises? Do I see Diamond Jozu with his entire body blocking a semi casual flying slash from Gol D Roger? But of course I do. Jozu's durability and physical strength rivals top tiers.
2.I don't think it was implied that Mihawk is attacking Luffy with an actual intent to kill as he was seemingly pulling great deal of punches. Instead it was more of an ordeal for Luffy, a test rather which if Luffy survives he passes said test and if he dies he fails said test. And Luffy did pass when Mihawk had an internal monologue while fighting, pointing to Luffy's scary ability of making people follow him that saved him from Mihawk not Luffy's combat might. It is same Luffy who walked out alive after challenging all three admirals at the same time. Yes I do believe same situation can occur with Gol D Roger.
3.Vista vs Mihawk was a clash that seemingly had no more intensity than an off panel clash that Zoro vs Fujitora had and it seemed less intense than the clash Oden and Prime Whitebeard, Gol D Roger's equal had. Worth noting a good deal of that fight, Mihawk was thinking about Luffy, not paying proper attention to Vista. I can see flower blade being able to pull the feat that Rookie Oden pulled against New Gate as I don't see Rookie Oden as that far above Prime Flower Blade Vista if at all.
4.Mihawk and Crocodile didn't have a clash, Crocodile seemingly tried attacking Mihawk and Mihawk deflected it and that was that. So not much to go by here.
Now there are few points in Mihawk's favor like Mihawk's casual nameless attack being one of the biggest feats in manga, and rivaling power of gura gura itself. It seemed superior than Gol D Roger's named attack on Oden which he tanked quite easily
Fact that Mihawk is one of the only two men in history to have armament Haki so strong that his blade has permanently turned black. Gol D Roger despite coating his blade in Ryou constantly, has failed to make his blade permanently black. That implies Mihawk's armament is better than Roger's.
Hawk Eye also has the title of Strongest Swordsman in the world but Roger doesn't despite being a Kenshi himself and the fact that Roronoa claimed he wants to be strongest swordsman ever and Mihawk is best candidate for Zoro's final challenge before him reaching his prime.
Though Roger's pirate king title demands respect so I place Roger slightly above Mihawk.
