What is the most famous McDonald's burger?

It depends which country and continent you are referring to. The normal Hamburgers and cheese burgers sell well because of happy meals. There is also the Angus burger which people are now starting to prefer. This is what I researched, though I am vegetarian. But, as I said, because of the happy meals, normal hamburgers and cheese burgers sell well. And the Big Mac and Angus Burger are becoming preferred burgers.