I'm going to say Springfield Armory Mil-Spec. I have only had a few failures out of 3000+ rounds. The failures were due to junk magazines ($5 GI specials) and learning proper grip. My Mil-Spec feeds hollowpoints, semi-wadcutter, and Wolf ammo without a hiccup. In contrast, my Springfield Ultra Compact and Para C6.45 will both feed hollowpoints but not swc or Wolf reliably. I figured that with the heavier springs, both smaller guns would feed everything. That was not the case.
I heard a rumor that the Springfield Mil-Spec pistols are not close enough tolerance for their premium lines. The tolerances generally meet or beat original military specs, so they still make great pistols. Springfield decided to incorporate a more economical line of pistols rather than scrap parts that were only a few thousandths shy of perfect. I have no idea if this is true, but it would make financial sense.
In any case, use good ammo, keep it clean, change the springs as needed, stay away from cheap magazines, and get it tuned by a pro if needed. These basic tips will make any 1911 run like a champ, unless you bought a real piece of crap. There are things even a pro can't economically fix.