Recommend you first settle on a caliber. Since you mentioned P320, G17 and G19, I might deduce you are looking for a 9mm, but I don't want to assume.

If that's the first criterion -- i.e. 9mm -- then next is budget. You don't have to be specific, but a price range helps narrow the field even more.
Lastly, you need to try a sampling of various brands and models. Personally, I'm a Sig supporter. The ergonomics of their main models really fit my hand and feel more natural than a Block. Having said that, not all Glocks are created equal. I prefer my G17 over my G30 and G26, just on ergonomics alone. The G19 isn't much different than the G17 for feel IMHO. if you aren't experimenting with the Glock removable backstraps to find the best fit for you, you're limiting yourself.
I can't talk bad about a good quality 1911, either. That's the "feel" all other pistols are compared to, because most people I know find a 1911 easy to shoot well -- even in ,45ACP.
If I had to rank order my personally-owned semi-autos (current and past), the list would be:
Sig P226 MK25 9mm
Sig P320 Full Size 9mm
Sig Nightmare 1911 Fastback .45ACP
Glock 17 9mm
Glock 26 9mm
Glock 30 Gen3 .45ACP
I'd rather spend a few hundred more for a Sig I like over any Glock. Just my own experience, of course.
I didn't get into Semi-autos for a very long time. Finally started about 2010. I bought Glocks because I didn't know any better, and Glocks were a better value feature-for-feature compared to many others. When you first start out, you tend to follow the folks who've been doing it for decades.
I know Hickok45 is a HUGE Glock fanboy. His videos helped persuade me to try Glock. After watching him for a few years, I've realized he's never met a firearm he didn't like (unless it malfunctioned on him!).
Striker-fired guns are the standard now as far as I can tell. The simpler design might reduce operator error and potential malfunctions.
If I were to choose a full size for home defense, it's my P226. If I carry a full-size for CCW, it would be the P320. Lighter and striker-fired, and the ergonomics are on par with the P226.
Also, with the P320, you can alter the pistol size (Full, Compact, etc.), caliber, and barrel length by swapping parts with the same registered trigger module. If you want a full size for HD and range practice, get that. Then get a Compact X-Change kit to make it more CCW friendly. If you only need one pistol at a time, it's a real money and "gun law hassle" saver.
Sights are subjective. Many are adopting the Red Dots now. You might want to "future proof" yours by getting one with a RDS cut slide and tall/suppressor-height sights.