User blog comment:AYET/The worth of the Shichibukai to the Marines 2/@comment-9787781-20140127113302/@comment-7890302-20140127134642

That's true... But for possibly the top 5. Marco has been stated multiple times to be stronger, and was shown to at least harm an admiral and fight them off, while other commanders were taken down with ease. Vista is arguably the bests swordsman among them. Ace however, I think is just as equal as the other commanders, rank doesn't mean power. Marco becoming captain, is a good indication though.