I suppose it depends on purpose. I used to shoot competitively, for fun, and for sport. Something happened to me somewhere along the line in my late 40s or early 50s where I just didn't enjoy shooting recreationally anymore. I transitioned into a utilitarian shooter. My firearms and stockpile are for the exclusive purposes of self protection, protection for those I love, to protect my castle, and to hunt so I can feed myself. All that being said, I have only a few select firearms with a minimum of 2,500 rounds per trigger. 7MM PRC, .556, 9MM, .45, 12 GA, and 22 LR. Each serves a specific purpose. However, my "favorite-all-time-caliber" would be .45.