Akainu wins extreme diff, marines strongest fighter isnt going to be a shichibukai, but the FA, Mihawk is going to be zoro final boss, while akainu is going to be luffy pre-final or final boss, considering the final war against the WG than the bond created between akainu and luffy will result in the final fight of these two, his importance to the story is bigger than what mihawks is, since the TS oda has been hyping akainu and BB nad even before ts, while mihawk is just some linear character who is there just to be beaten, I doubt we will even see a backtstory about him, there is even the chance of shilliew taking his head and fight zoro for the final war, that being said akainu importance is bigger than Mihawk and at this rate bigger than any yonko except BB, oda even had the interview that if akainu was a protagonist he would get to OP in 1 year time, hes been hyped up since the ts as the main fighter of luffy together with BB, oh and Mihawk fighting shanks is a complete ? in my mind, he may have fought a young shanks, but its been like 10-15 years since shanks lost his arm, and Mihawk stopped dueling him, 10 years time can make a character grow from fodder to top tier, not saying shanks was fodder but definitely weaker than a yonko level.
Akainu went toe to toe with the WSM, stronger than any yonko, to think that he cant fight yonkos on par is just some fanboys who tend to dickride the yonkos without a single feat but try to compare them to WB even though manga has told us that WB>anyone, u cant argue with fanboys, thats a rule.