A quick comment on the Springfield XD– a friend of mine purchased one recently and has been completely unable to acquire spare parts for it! Springfield will only sell spare parts to certified XD armorers– and word is that there are none of those yet. As of now, the market is limited to (Wolff) recoil springs, spare mags, and components such as replacement sights.
So if something breaks, you have to ship your pistol to the manufacturer. Now, random parts breakage is fairly rare, but this is the death knell for these guns, in my opinion, as a serious survival sidearm. Hopefully, this will change in the future with readily-available spares.
In my personal opinion, one should, at the very least, focus on a core battery of weapons that have easily obtainable spare parts and bulk ammunition. Not in the future, but NOW, when you buy the gun. A pistol with a broken firing pin is a paperweight. A rifle with a faulty extractor has very limited use. Etc.
The reason that I recommend Glocks as survival arms is that a mentally deficient ape such as myself can maintain them with ease. Very easy to work on! Parts are readily-available and inexpensive. You can easily rebuild the entire weapon down to the smallest part, by yourself, with the basic Glock takedown tool. And the most robust and versatile of the Glocks, in my opinion, are the 9mm variants, the 17 and 19 in particular. A police trade-in, ten magazines, five sets of each spring in the weapon, and a bundle of spare extractors, firing pins, et cetera will not set you back too much.
1911s have more of a learning curve, repair-wise, but again, parts are readily available and basic parts replacement is fairly easy for handy people (hand-fitting aside). Not as easy as the Glock, but with a mentor, you can do it.
My personal favorite handgun is a Steyr M40, which I also consider superior to a Glock– academically. But from now on, I am transitioning to the Glock 9mm variants for the reasons above. Regards, – SomeGuy