While it's true that wagyu beef filet mignons and Wagyu strip steaks are more tender, top sirloins are more affordable, still tender, and offer excellent flavor.
Top sirloin steaks are typically cut in one of two styles: "baseball" or "strip". These top sirloin steaks are "baseball cut" (aka "filet cut"), so they're shaped a bit like a filet mignon (tall and narrow).
Wagyu beef (aka Australian kobe beef, kobe-style beef) is from a breed of cattle descended from Japanese herds & specially raised in Australia to increase its percentage of fat marbling to consistently high levels. More marbling leads to more flavor, tenderness, and moisture as the fat melts during the cooking process. Thus, wagyu top sirloin steaks are both more flavorful and more tender than those cut from conventional beef.