"What I need" in a retirement CCW handgun carried for defensive purpose is pretty simple for me ...
It has to allow for being comfortably and easily carried when I'm engaged in my assorted daily activities. Yes, I know the adage about how a defensive pistol is meant to be comforting and not comfortable, but I spent a career in LE carrying weapons both in uniform and plainclothes, as well as off-duty, and I have some experience in determining whether or not I feel it necessary or appropriate to carry a full-size service weapon. Also, many of the more modern platforms are coming in acceptably smaller and lighter configurations which function well and serve the needs of many users almost as well, if not as well, as larger models. Pick what you like ... I do.
I also have a 'threshold' minimum caliber preference ... and it's also .38 S&W Special or 9mm. I have a fair number of guns chambered in more powerful calibers, but those are my personal 'minimum' calibers.
I have and use both revolvers and semiauto pistols. I train & practice with both. My selections in semiauto pistols includes some different designs with which I've gained a fair amount of familiarity & practice. Some folks may prefer a much more limited selection, or restrict themselves to just one design. That's fine. They should choose for themselves. I do.
I require that my defensive handguns be reliable, accurate & durable under reasonably common conditions with normal maintenance practices.
I prefer guns made by major makers of handguns who have gained experience having provided weapons to LE/Gov users, and who have proven themselves willing to strongly support their customers in the way of fast & easy warranty service and/or armorer training and parts support.
I don't get too wrapped up around the axle debating make/model/caliber from a user preference or simple personal opinions. There are a number of good quality makes/models out there being made by the major companies who have earned respect and trust over the years.
As a LE firearms instructor of a couple of decades experience I'm familiar with the discussions and thoughts regarding many of the advantages and disadvantages of ammunition capacity and reloading.
That being said, I don't lose any sleep over carrying handguns with capacities of either 5 rounds in revolvers or pistols which have mag capacities of 6, 7, 8, 9 or 10 rounds. Over the course of my career I started out carrying 6-shot revolvers, and then once we changed over to pistols I carried issued 9mm, .40 S&W and .45 ACP guns which at one time or another had mag capacities of 14, 15, 12, 9, 8 & 7 rounds, in just about that order. I finished my career carrying an issued .45 which used 7-rd mags. Capacity just hasn't been all that much of a critical issue for me.
Skillsets developed from training & practice have always been more critical considerations for me than the actual weapon/equipment ... right behind mindset, awareness, knowledge/tactics & mental/physical preparation.
It's just a handgun.