The signature feature of any pro-style range is one or more burners capable of super-high heat for searing, sautéing, and fast boiling. But don't get too hung up on the number of Btus. For most home chefs, 18,000 Btus is plenty hot. Remember, too, that a bigger number doesn't necessarily translate to better performance; it all depends on the quality of the burner and controls.
Equally important is a burner that can handle delicate tasks, like simmering an untended pot of chili all afternoon without bringing it to a boil—or a burn. Different manufacturers use different technologies to achieve a steady, even heat, typically putting out 350 to 850 Btus. So be sure to test the simmer before you buy.