The operator can also affect reliability in several ways. Auto pistols can jam from the notorious "limp-wristing" problem. Actually, this is often "limp arming." Whatever, it causes operator induced problems, and it isn't the fault of the gun. The solution is a strong stance and a high, firm grip. Just as the gun is a system, proper stance and grip on the gun are also parts of the operator interface system. Also, the way the hands grip the gun can cause reliability problems. I've seen finger and thumb placements that have put pressure on the auto pistol slide release, causing the slide to lock open after every shot. I've seen grips that put pressure on mag releases and cause the magazines to drop out, or not drop out when you're trying to reload. Or grips that inadvertently activate manual safeties, or don't deactivate grip safeties. I even know of a few folks who accidentally hit the cylinder release on revolvers. Often, a gun can simply be too big or, yes, even too small for someone's hands. Any of these things are genuine problems that affect the reliability of a gun at the moment that you urgently need it to function. The solution is to alter the interface or change to a gun that doesn't contribute to the problem.
What I'm saying here is that reliability is not just a single dimension, addressed by simply using a good quality firearm. All guns are not the same for all people. And the solutions are not the same for all people. This can become obvious in police service pistols where "the same gun for everybody" is the norm. There are vast differences in individual users and considerable variation in training programs. Combine this with both firearms and ammunition purchased through "lowest bid" contracts and all sorts of problems can arise. Remember, reliability, most of all, means that when you need it, you have confidence that your gun will work. If you have addressed the possible problems in advance, then your confidence is well placed. If you have not, there can be a terrible price to pay.
As you can see, if someone asks me what gun they should buy or use, they don't get a one-size-fits-all answer. No matter how much I may like or dislike a particular firearm, you may find just the opposite. That's fine with me. My job, as an instructor, is to help you find the right gun for you. There is only one "best" gun, and that's the one that works for you when you need it.