Who was the strongest Hokage?

I believe it was the fourth. I know people claim he wasnt strong enough to defeat the nine tailed fox, but if you read the manga you will see that he sealed it inside naruto so that he could use it to defeat mandara uchiha. He also went toe-toe with mandara and won which made him retreat. Although many people will say the 1st because he was also able to fight and defeat mandara and the tailed beast so if you think about it it could go either way.