Back when I was a freshman in high school and didn't have a drivers license yet, I'd walk to McDonald's every day for lunch with a group of buddies because it was reasonably close to the school and the price of a quarter pounder with cheese meal was $2.99 - about the same as worse cafeteria food. Since I got my license, McDonald's has been my last choice of fast food stops - only when there are no other options (like when I'm traveling and need to stop in the middle of nowhere) or someone else in my party special-requested it (like when my daughter was little and wanted McD's nuggets as a birthday meal).
If I'm traveling, I'd choose BK over McDs, but if I'm in Oshkosh and someone gives me the choice of free food only from McDs or BK I'd choose McDs. The BKs in Oshkosh are the worst. Really, though, I'd rather pay for my own food somewhere else than patronize either one.