There is no perfect handgun for self defense. It's best to have options from small guns to full size guns. Obviously, if the other shoe drops, everyone wants a powerful gun that never jams and never runs out of bullets, with sights that make it impossible for you miss.
But the reality of it is "what are you willing to carry, day in and day out, and what is your perceived risks?" Does your lifestyle, job, etc require deep concealment, you name it?
Anymore, there is a virtual sea of tiny, to large semi-autos on the market, many are quite good, but many also have flaws that if not identified and dealt with, could get you killed. One thing I have noticed is that there are several models out there that can very easily have their magazine disengaged while carrying and leave you with a gun that only fires once or none at all. And jams can and still do occur even with top quality brand names. And even if you do need a reload, if you don't carry that reload in a very fool proof and accessible location, it will probably never be employed anyway because there won't be time.
Few of these problems affect the revolver, and the round count will probably be enough, assuming the operator can shoot, and if you do run out of ammo, maybe it's time to draw another handgun for a NY reload. At any rate, extended shootouts are rare for the common individual, and shop keepers and law enforcement is a different matter, and the risks and probabilities are usually very different.
You just have to decide what you can carry, how to carry it for fast deployment, and know you individual choice well enough to have confidence that it will work for you if you ever need it. If I carry a revolver, I like another back up revolver, even if it's nothing more then a NAA Mini 22 mag accessible with the other hand. Same if I carry a small automatic, even if I do have a spare mag. I would rather have a spare gun then a spare reload, but like to have both for CCW.
The farther I travel out of my sphere of influence the bigger the gun I want on me, if I have a choice. If I am traveling and it's a lonely gas stop at night on I-10 or somewhere, then I want my 45ACP, Lightweight Commander in a good holster, and a reload, and nothing smaller gives me much comfort. But locally, I can be quite happy with a 5 shot Air Weight, and maybe a backup mini-revolver, or even another Air Weight if clothing allows for it, and to hell with the reload.