53 years and counting. US Army M1911A-1, Colt Government Model, Colt Commander (LW and steel), Springfield Armory, Kimber, full-size and compacts, .45, .38 Super, .22LR.
I have always gone back to the full-size 5" and .45 caliber. There is not much difference in bulk or weight. The pistol design is remarkably low in profile and relatively easy to conceal when necessary.
Past 20-plus years I have been using a Kimber Custom CDP full-size 5" .45 ACP loaded with just about all the bells and whistles that custom shops developed for combat use over the years. Alloy frame shaves a few ounces off the total package, but not so much that it is really noticeable in daily use. 3/4" overall length means very little in comfort or concealment. Maybe it's only me, but the longer sight radius of the full-size model is a plus for accurate shooting. The higher profile sights are a great improvement over the original 1911 design.
It could be nothing more than familiarity starting out in the Army, through a couple of tours in Vietnam, and just about always having a full-size .45 ready for use. I always know exactly what to expect, exactly what to do. I suppose that the pistol has simply become an extension of my hands, arms, and mind.
For what it may be worth, I have similar feelings about the K-frame Smith & Wesson revolvers. Not much in the way of improvement is possible, and over a century of demonstrated excellence.