If you remember back to their post about phone price deprecation (http://priceonomics.com/phones/#cell-phone-depreciation), you might recall their statement that, "... we firmly believe that resale value is the best objective indicator of product quality." In this current article, they state that "... the popular Bose QuietComfort 15 stood out as having the best resale value."
There you have it: incontrovertible proof that the Bose QuietComfort 15 is the highest quality headphones in the sample set.