"Self Defense."
Lacking any other description of it's use, we are left with the most common interpretation. If you plan to defend yourself out and about your 1,000 acre ranch, plenty carry a rifle. Having indicated a pistol, it's more likely an urban setting, and with 9mm, it's an inexpensive enough and plentiful round available in a lot of loadings.
So far, no foul. So, if it's "self defense," it's likely not at home, it's out and about town or a city, which means carry on body to maximize having a gun to defend yourself at all times. It does little good to have it in the car or a locker when you need it. All common conceptions of what we all do carrying in "self defense." Lacking any other explanation or clarification, I see the OP asking about what to carry in daily life.
It's arguable it's not concealed at all, which would make the choice of any of the four acceptable. An OWB gun carried on the belt. What comes into consideration is if that is what he wants - a double stack duty gun with over 15 rounds of ammunition on his belt, all day long.
Most who don't have to carry that way on duty choose a lighter firearm. It's a comfort issue, we don't wear heavy soled biker or woodcutter's boot every day for just a fashion statement, and as we get older, we change. Those who carry a large double stack auto pistol have frequently reported they eventually move down in barrel length and capacity. It happens to meet their level of comfort.
That's why it comes into question whether a double stack large frame pistol is the ideal. Sure, it works for some. It also does not work for others. And in their experience, they came to different decisions.
First, self defense statistics show that most urban confrontations happen at close range - three feet. Most have about three shots fired. And most of the firing happens in less than three seconds, which doesn't mean that the individuals involved weren't in conversation for a longer time. What happened was that one determined the other was presenting a lethal threat, drew, and fired.
Under those specific conditions, the double stack large frame duty gun offers no direct overpowering advantages compared to a smaller, single stack gun. It might carry more ammo, but less than seven rounds meets the requirements. It might have a longer sight radius, but at "whites of their eyes distance," getting a sight picture may be more endangering as it extends the gun into their zone of entrapment. No sights at all are not unusual in carry guns.
It boils down to how the user wants to operate the trigger - and whether a safety is engaged, or not. Two big schools of thought on that. First, does he want a light or heavy trigger pull, second, does he want the safety one requires, or not? The pistols chosen offer both.
High Power - SA
CZ75b - SA/DA
HK USP - SA - DA or combinations
G19 - semi cocked DA
Most of the other features are similar, the issue is what trigger the OP prefers, and whether a safety should be involved separately from the trigger.
We can recommend any one of the pistols, or a revolver, the issue really rests with the OP - what does he prefer in triggers and safeties?