The Sig P226 and the .357 SIG have a great reputation. The P266 is a proven Navy SEAL sidearm. I don’t fire the .357 SIG often, but it is a high-energy round, almost as powerful as the 357 magnum while being more controllable. Its downside is that it’s fairly new and relatively rare, so in a social collapse situation, finding more ammo may prove difficult.
p.s. Another downside: the 357 SIG is also much more expensive than the 9mm, so you won’t have as much ammo for practice.