Cook Out is one of the best regional fast food chains I've ever had the experience of trying. Cook Out is inexpensive, great food served quickly with a smile. And the variety of food is amazing.
Trust me on this -- the "tray" at Cook Out is the best fast food value anywhere. Your choice of entrees (and there are quite a few), two sides, and a drink for under $6.
When you combine that with the variety of food, shake flavors, and late hours, there's no better option out there. If there's a downside at all, it's that most of their locations are to-go only.