The BEST carry gun and holster is the one that you can:
1) get to quickly
2) hit a 2” target consistently at 10 feet (if you cant, you need either a smaller gun or more practice)
3) and perform #1 and #2 under high stress
A .22 revolver that is fired accurately at a vital spot is a whole lot more devastating to an opponent than a .50AE or .45ACP fired in the wrong place, or misses entirely.
Other additional considerations:
weight
comfort
conceal-ability
reliability
cost
Not sure ya need TWO INCH accuracy as a spec, particularly in a high-stress, perp-in-motion, self-defense shooting scenario.
If I am hitting roughly center mass, particularly upper torso, with 6 - 12” (picnic plate outlines on the Barney Fife target) 3-round quick-fire groups, at 12 - 15 feet, I am happy with that, and pretty certain the .45 rounds WILL stop the threat.