The loin yields the most tender and expensive cuts of beef–but not the most flavorful. The choicest portion is the tenderloin, which is exquisitely tender and lean. The top loin and sirloin aren’t as tender, but they’re a bit more flavorful. Cuts from the loin require very little work to taste great. Indeed, steak lovers consider it almost a sacrilege to marinate them, or to cook them beyond medium rare.