Caliber really doesn't matter. I don't want to be shot with a .22. 9 mm is probably the best overall round. Its semi affordable at around a buck a round for carry ammo. I am shocked to see all the .357 sig carriers. You can barely find .357 sig ammo. As many said the gun you willl carry and PRACTICE with is the best gun. I have a 10mm /.40 but I rarely practice with it since ammo is ridiculously expensive. My EDC is a sig p365x. You can carry it with any clothing. I like my Canik Elite but the 3.7 inch barrel digs into my thigh/crotch a bit too much while driving. In winter it will be fine.