The firearm I would most trust my life to is the one I carry 24/7: a S&W 642 on my ankle.
Oh, to be sure, where the law allows, or where private property owners allow, I augment the 642 with either a 1911 or a S&W 686, both of which I "trust my life to." At home I am seconds away from bringing either a 12 ga. pump or AK-47 into action, either of which I also "trust my life to." But the item I carry everyday, everywhere, is the tiny .38 snubbie.