There are some restaurants that are inextricably linked to their most popular item, like Domino's pizza or Shake Shack's burgers. They serve food that you don't even think twice about ordering because it's their area of expertise. Why go to Chipotle and not get a burrito or wait in line for In N Out and skip the burger? That is, more often than not, the correct thing to order.
But there are some places where a lesser-known item on the menu is better than the signature dish. Sure, taste is a matter of (ahem) taste. But, if you've ever had the banana pudding at Magnolia, you cannot possibly tell us with a straight face that their cupcakes are better — and that's before we even get to chains like Taco Bell, Starbucks, and California Pizza Kitchen.