Who decides who the “best” is?

This is the word that has started to annoy me quite a bit (but who cares if it annoys me, I mean I am nobody for anybody). Why? Because everybody wants to be the best at something. When I move around the city of New York, I see signs like the best Pizza in town, the best burger in town, best this and best that and you may also have encountered in the U.S. and other countries. We are a being obsessed with being the best at something and we don’t stop at anything to achieve it including false advertising and twisted sense of self adoration. But who decides who the best is? Does some random customers which may be a few of them say that they are the best and then the company says that they have the best Pizza in town or the best burger or whatever best they are claiming to be. Did they enter into any official competition that decides who is the best in its class of products or services. To me, being the best is just a subjective matter open to interpretation and an individual's own decision. You can call yourself best but how did you make that conclusion? Did your customers or some top level experts in their field went to your place along with hundreds of others like to make that decision and even if they did, maybe you are not the best, but one of the best in your field, does it not satisfy you that you are one of the best or you keep on drumming your name as being the best because it is your products and not anybody's else.