User blog comment:AYET/Other talks about chapter 747/@comment-10543621-20140515065855/@comment-4754162-20140516044637

Got a point, crews with genuine bond with each other should be really successful and strong. Luffy, Shanks, WB and Roger are examples, Doffy has just been revealed to be one as well.

That could also be one reason why CP9 was one of the best and most difficult team for the Strawhats to overcome. Yes, Donquixote pirates may be the best toughest yet (which is also logical in chronology of the series, I mean you can only get stronger and stronger adversaries as the series progress)