Five guys definitely has some decent burgers and fries. I love that you can add a mess load of toppings and the burgers are huge! (if it's your first time, know that the regular burger is 2 patties and the little is 1. Didn't know that my first time!)
I usually get A1 sauce, jalapenos, mushrooms, lettuce, tomato, ketchup, grilled onions and cheese on my burger which tastes exactly how I like. The problem for me is that they always wrap the burger in aluminum foil!! By the time you sit down and open it, the bun is soggy, mishapen, and the whole thing is not as good. -_- I wish they would just wrap it how they do at In-n-out.
The fries are really good. I like them better than the in-n-out ones. Definitely go for the cajun spices. Makes the fries way better!