It’s known that firearms can serve for a long time after they’re no longer cutting edge. Flintlocks held on long into the percussion era. During the American Civil War, plenty of cavalry units, especially local militias, turned up with single-shot pistols despite Colt’s revolvers having been on the market for a while by then.
When it comes down to it, if you're going to have only one revolver, the .357 Magnum is probably the best option.
If your practice sessions are limited, make sure every round counts.
Selecting a personal-defense handgun is a very subjective endeavor.