A "bug out" pistol for me would be a have the following characteristics
- Medium-Full capacity and frame
Period. I love 1911s, steel framed guns, revolvers, and am quite happy shooting larger calibers. But...
guns are light (critical), generally high capacity, and endure a great deal of abuse and even neglect. Medium-Full
because I want to carry max rounds within the gun as opposed to a multitude of extra boxes/mags of ammo. I also want a firearm I can precisely control. 9mm
because it's an adequate defense round, is the easiest centerfire caliber to track down, and because it fits nicely with the two previously mentioned theories involving weight and capacity.
That's just my perspective. For me it'd be an XDm9. But a similarly designed Glock, S&W, etc would suffice.