I would go to the one that offered the best vegetarian selection I love the ice cream at McDonalds and their vegi burgers, KFC have nice desserts too but they don't have much for vegetarians and each time i've been in 95% the ice cream machine has been broken
Subway are very popular in my area and Burger King are good too. I haven't been to the other ones, but out of all of them if I had to choose it would be McDonalds for their vegetarian selection and their ice cream