What do you think Is the best Hi-cap 9mm pistol for the times we live in?
There is no universal or absolute best. It is silly to try and say otherwise. The reality is that there are many many 9x19 offerings that are more capable than the vast majority of would be owners. If you have the opportunity to be around people who can really shoot you will notice that they can run a very large variety of guns very well. I've been in a class with an instructor who has used three different makes of guns over the duration of the multi day class and shot lights out with each.
The floor is having a reliable gun that you can and will carry with you. Beyond that a lot of it is personal preference and deciding on which trade offs to make.
Then there are considerations such as whether the type of holster or light you want is compatible with the gun you want. I was giving a P30 SK a real hard look until I learned the XC1 surefire wont fit on its rail. I have a gun I like to carry and think highly of. Yet only recently has a quality AIBW holster that accommodates that gun with an XC1 mounted become available.
Some people are really wanted to be able to run an RMR on a handgun as they feel it offers a distinct advantage for certain tasks. Some guns are better options for mounting an RMR than others.
Generally speaking there are many very good choices. Personally if I was only going to have on 9x19 pistol it would most likely be a Glock 19. It is a very efficient size. Mags and parts are super easy to find and at reasonable prices. Any neat new thing such as the XC1 light or a great new holster design is typically available for it.
The reality is that any of the popular and proven designs are fine, but you may have preferences that lead you to like one over another.
The main reason is that if you modify a gun, and use it, there is a good chance it will go against you in court. Therefore the carry gun I use must be stock.
I advise others to do likewise. Speaking to a Marine, "retired sniper instructor" who I shoot with, he purposely buys ammo that says "home defense". or something similar, on it, for that very reason.
when you start tricking out your carry gun it doesn't look good in court, which is where you are going I you shoot someone even if it's justified most times.
Please provide the following:
Your legal training and credentials.
Your experience in criminal law generally and self defense cases specifically.
Any examples of a case where this was even brought up? Any examples where it played a significant role.
Any supporting evidence for the idea that you are headed to court most of the time even if a shooting is "justified."
Frankly all of that is unsubstantiated at best and more likely sheer poppycock regurgitated from other people who don't know what they are talking about.