All the National Polling in the United States, for many years, have been all been in agreement that of all "Over The Counter Coffee Fresh Brewed Coffee", "Ducking Donut" Coffee is still the #1 in all the ratings...
If they all agreed, then they're all wrong!

Really, though, replace coffee with beer, and in a nationwide poll you're still pretty much limiting your results to the nationally available brews, and eliminating all of the (likely) vastly superior microbrews and locally distributed craft beers. Likewise, there's plenty of places tht will pour you a better coffee than DD, but they're not national chains.

That's like saying that "national polling in the US consistently agrees that Cabelas and BPS are #1 in fly fishing related sales" so they must be better than the guy with that little place on the creek that you've been visiting for decades.