User blog comment:Firefist553/the 4th strongest/@comment-3130944-20110520153720/@comment-3387274-20110521072550

I'm pretty sure Zoro is fractionally stronger, or at least was before the timeskip. He has much greater endurance than Sanji, and always fought the second strongest member of the enemy crew, while Sanji got third.

However as a trade off Sanji was so much better at not getting injured, and indeed finished his fights by walking off with a witty comment, whereas Zoro generally dealt with anything important and then fainted.