We know that I have the "World's Best Sigma", but Shihan has the "World's Greatest Sigma". My "World's Greatest" handgun is a Springfield Armory parkerized I purchased over 25 years ago that I've butchered, rebuilt several times, and has lead me on a path that is never ending to find one better. A friend has a "Looking Glass" in .25ACP that his father liberated from a German officer during WWII. In fact, it is the only firearm he has. What is your "World's Greatest"?