Burger King, I would say. McDonalds has slightly better fries, but their burgers are very mediocre- their grilled chicken sandwiches are nice, but not as nice as Burger King's burgers. (TBH Hardee's whoops all other fast food in terms of quality, but most of their restaurants are located in the Central/East US so not everyone is familiar with 'em)
McDonalds fails. I tried my first cheeseburger there, and didnt eat another one for a long time. There was this strange clear gooey un-chewable slop inside it. Disgusting.
Ugh, who eats at those places anyway? I bet half of you don't fully understand what is going into your bodies. S'all trans-fat's, swine nose, foot, other low cost parts etc...
Anyway, Burger King is proboably the least unhealthy of the two.