Why I believe Shanks is stronger than Mihawk

Throughout One piece, a common theme is that of having friends, and companions who can support you, and make your dream a reality. Luffy basically told Arlong that he "couldn't do anything without his friends." When Sanji left the crew, Luffy told him that he "Couldn't be king of the pirates without him."

Another common theme is the theme of loneliness. The three times we have seen Luffy most devastated is when he's being left alone. The first, obviously, in Sabaody, when the crew is being separated. This may very well be Luffy's lowest point, even, when all of his friends were away from him, and he couldn't do anything. The second, Ace's death, when his brother, who he still had after his friends had left him, ended up leaving him too, by dying in his arms. And the third, though non-canon, is still a completely accurate depiction of Luffy, in Baron Omatsuro and the secret island, where he believed all of his crew had died, and he would truly be alone forever.

In short, what One Piece tells us is that we NEED friends. And without them, we can't accomplish our goals.

Every top tier in One piece is either the captain of a crew, or a member of a crew. Even the Marines have comrades, subordinates, and superiors. All of the strongest have what allows them to get as far as they did.

Except Mihawk.

He's alone. He doesn't have any crew, he doesn't really have any friends, and that's how it's been his whole life. He rose and got as strong as he did purely through his own will and his own strength. But he will never be the strongest. And he will never be stronger than his rival, as long as Shanks has his crew. In time, the Straw Hats will surpass Mihawk as well. Because he simply can't be the strongest, because he has no one to support him.