Toss up between flank steak or sirloin. Tend to like steak for the flavor not the tenderness (for as long as I have my own teeth.) If I had to eat one steak and one only for the rest of my life it would be the NY Strip. I've always thought Tenderloin and Prime Rib are overrated. Tenderloin in one of the least used muscle in the cow therefore being tender but having the least flavor. Prime Rib is a waste of a good ribeye.