It might not be that way where you live, but in my town, and in MY opinion, McDonald's tastes better than Burger King. We have 1 MD and 1 BK. Not too much to go on statistics wise, but oh well.
But out of all the large fast food franchises in my town, the single Burger King is probably the worst one to get a burger at here, ngl. We have a very popular local, national burger joint franchise which is close to 60 years old now. That one trumps BK and MD by a mile.
But of course, just go to any truly local spots that do smash burgers and you'll beat the big ones by a parsec. So good.