Hate to say this about a US chain, but 5 guys has the best burger in Cowtown. Burgers are a little messy when you have them 'all the way' like I did so it may not be the best place for a first date, but the ingredients are fresh, the all-beef patties are cooked to perfection and delicious, and the fries taste like they should in a perfect world.
Word of warning - I'm a big guy and I love food, and I order the 'little' burger. When you look at their menu (which basically has 4 items on it) it may look expensive, but trust me you get more than what you pay for.