Well, aging hands are a factor. Retiree-level income, though “comfortable” income, is a factor. So:
Cartridge: Well, slow-accelerating, rather than snappy. I wrecked my hands, especially my right hand, during my seemingly-immortal twenties, during the Eighties, firing big-bore Magnum N-Frames, with my K-L-Frame-sized hands. Even though I grew out of that, by age 30, by my early forties, I was starting to feel it, and stopped shooting some “compact nines.” By age fifty, there were some duty-sized .40 pistols that were becoming painful to shoot. My SIG P229 duty pistol is now simply a collectible/artifact. I can still shoot the low-bore-axis, recoil-damping steel-frame, full-sized 1911, with gently-accelerating .45 ACP.
Slide, if auto-loader, readily grasp-able, and not too difficult to “run.”
Width/volume: Well, the grip should be neither too narrow, nor too wide. “Hand-filling” is good. Protuberances, such as “gas pedal” controls, are not desirable.
Accuracy: Well, the more accurate, the better. 3” at 50 yards is a nice goal, if a target gun. A defensive handgun, with low-profile sights, need not be that capable.
Sights: Well, suitable for the intended task.
Manual Safety: Well, yes, if a 1911. My right thumb WILL reliably detenct and operate a 1911 safety. Otherwise, I will probably not want a safety lever, but, I will evaluate each, on a case-by-case basis.
Color/Finish: Well, it depends upon use case.
Optic: The desirability of an optic depends upon the use case. My eyes “demand” a large window. Better to have nice, bold-pattern irons, than an miniaturized optic. The Aimpoint ACRO P-1/P-2 are decent, for my eyes. Aimpoint Micro is better.
Frame: Metal, if revolver. Glocks are just too useful to ignore, so, high-quality polymer is OK. My next pistol may well be a Glock G34. I have countless thousands of rounds of rounds fired, through Glocks, to hard-wire my brain and nervouse system. I made some memorable hits, with “simunition” Glocks, during live-action/force-on-force training. Real adrenaline-dump-level training.
Grip material: Well, I am open-minded. Austrian polymer to walnut. All good, in their own ways.
Track record: Well, I would rather that a weapon system prove itself, over multiple years, and that the brand have a well-established track record, with NO recent changes in ownership or management.
There is nothing quite like blue steel and walnut, aesthetically, but I find beauty and utility in stainless steel, with laminated wood grips, to use my newest acquisition, a Ruger Single Six, as an example. And, Glocks, with full-duty-sized grip frames, are my “orthopedic” pistols, if my right hand is going to be training with it. (I will still fire G19 and G26 Glocks with my still-healthier left hand.)