Best is a qualitative term. What is best to some isn't necessarily best to all. Some want greater numbers while others want greater authenticity. Numbers and authenticity tend to be on opposite ends of the spectrum.
Also, don't make the mistake of ignoring the west. Events occur out there, too.
"While the original battle [Gettysburg] may arguably be considered the epicenter of the history of the war, the GAC reenactment is not the epicenter of the hobby. To confuse or equate the two is unfortunate. - Bernard Biederman, 6 July 2012
"Authenticity conflicts occur when reenactors from one end of the spectrum attend events at the other end of the spectrum then try to impose their own standards instead of event standards."