[quote=Spiritblitz]
....It's kinda hard to say. But realistically, Gildarts. Because of his Magical abilities. If he didn't have them, then Shanks.
[/quote]

Ehhhhh... I don't know. Even with magical abilities, Shanks is on par with Dragon, who's the most wanted man in the world. And keep in mind that we have no idea if Shanks has any Devil Fruit powers or not, which means that he could have equal magical strength.