Burger chains are the biggest business in the restaurant industry, pulling in $69 billion in sales each year. Nearly nine in 10 consumers say they grab burgers away from home at least once a month. Half of that business goes to McDonald's -- the behemoth that in recent years has upgraded its sandwich offerings, followed quickly by other fast food giants such as Burger King, Wendy's and Carl's Jr. But Six Dollar Burgers, Big Macs and Whoppers still leave many foodies uninspired, driving demand for chains that offer convenient, affordable burgers that are also thoughtfully made with high-quality ingredients. Cue the horde of "better burgers," which have begun beefing up the industry with premium toppings, fresher meats, better service -- and often higher prices. Their fans are fiercely loyal, their detractors often vicious. While the overall burger segment grew 3.7% last year, fast casual chains exploded 20.8%, according to a report from research group Technomic. Here, a look at some of the top better burger brands, including Smashburger, In-N-Out and Five Guys.