Also considering a Glock 17
Glock 17, or 47 (assuming you can get Gen5), or Walther PDP. Other options for Polymer striker guns: S&W M&P 2.0, CZ P10, or Beretta APX. If carry size is an issue you can go down to a Glock 19, or its' analogue in the other brands.
As someone else suggested, see if you can find a rental range, or a gun store with a rental range. Frequently they give a discount on a gun after a rental, or give a free rental with a purchase. Keep in mind that since you are brand new, you still don't have the experience to know if a gun is comfortable long term or not so you can't make a goldilocks decision yet. You kinda have to dive in on a platform and go from there. You should be able to get along with any of the above.
or a Beretta 92FS. (not striker-fired but I don't think double action would be too difficult to get used to)
You could go with a metal frame DA/SA, but it is a different class of gun which is more expensive, has less options, and more difficult to shoot well for a lot of shooters. The Beretta 92 series has had a bit or a resurgence recently due to the Langdon Tactical Models, but it all looks like gun hipster shit to me. Never been particularly impressed with the 92, and pretty sure they have issues with locking blocks breaking.
I just figured .45 ACP might be the move to maximize potential stopping power with the limited ammunition permitted.
Immediately stopping, or not stopping, a person all depends on shot placement and penetration into specific parts of the anatomy. Larger diameter bullets are seldom the deciding factor in that. Many assailants stop after non-fatal, non-disabling wounds, because they realize they don't like being shot. That's as short as I can keep it without going into a long 9mm vs 45ACP spergout.
I have tried all of these (Striker, DA/SA, 1911 in 9mm, .40, and .45) over many years, and come back to the Polymer 9mm striker guns listed above. I would still do the same with a 10 round limit.
There's literally nothing wrong with 1911's
The majority of manufacturers don't put in the level of quality, and detail that a 1911 deserves. Yes, the triggers are nice, and the heft contributes to an easy to shoot gun. But it is still a long, heavy, eight round gun that can be very picky about certain things. It's a level of user knowledge, and maintenance that isn't for most beginners. It's a steep learning curve on the inner workings of the gun.