It’s not the bun I worry about.... It’s the crappy tasting burger they put in those things.
Seriously, I gave up on everything BK decades ago. They just plain suck!
I like Johnny Rockets burgers, they are pretty tasty. We also have a place here called The Burger Lounge, the meat is supposed to be “Grass Fed” and Organic thus healthier, its alright I guess nothing special.