A note to the OP - if you had to hit someone with your gun, would you prefer an "all steel" gun or a polymer substitute? Which is least likely to be adversely affected?
A) They’re both going to be adversely affected if you use the mag baseplate to strike someone. The follower is likely to continue moving downwards with inertia and the ammo in the mag will not stay aligned correctly - leading to failures to feed.
B) Training is important. If they’re within arms reach and you have a gun out, you should be in a retention / pectoral index position and keeping the gun away from them, not striking them with the gun like some ‘80’s action movie.
C) If for some reason you do have to strike someone with the gun, hit them with the top of the slide. Conveniently that also solves the “steel vs polymer” issue.
To the OP:
My recommendation would be to go with a Glock 19 or 17. They’re both 9mm so you’ll have slightly less expensive ammo (a benefit for training and practice) and there’s not enough difference in terminal effect to justify the increased recoil or the reduced capacity of other calibers.
I would also advise you get the MOS version that can accept a red dot. That doesn’t mean you need to put a dot on the gun immediately, but if you ever do decide to try one your gun would be ready. If you do decide you want an optic, use an aftermarket plate - the MOS plates have a reputation for failure.
The PDP is a great choice as well (I actually use one for carry and competition). Only potential issue would be what is allowed by your employer/local/state policies. If they allow semi-autos you’re almost guaranteed that a Glock will be in the list of approved weapons. The PDP is new enough that it may or may not be included. No reason it shouldn’t be, but the Glock is always a safe bet.
Revolvers are nice and fun, but I would not recommend them as a duty weapon - they’re not the “always reliable” option that a lot of people envision. A little dirt under the ejector, or a bit of fouling between the crane and cylinder and you can really lock up a revolver.
Semi-autos do jam, but your training and practice should cover how to reflexively fix those issues. The only immediate action drill for a real revolver jam usually incorporates some form of “gee, I hope I brought another one…”
Get a Safariland retention holster. As noted in a previous post, gun grabs can happen and you want to make sure that your holster will not fall apart when force is applied to it.
And more important than anything above - get good training.
Not just the armed security officer required course, not a NRA basic course, go to a well known school that actually teaches you to fight with a gun.
Also consider doing something like USPSA with your duty gear. No you won’t win competitions (especially if you’re using a retention holster) and it is certainly not a replacement for training, but it is an excellent way to gain familiarity with your weapon and gear in an environment that promotes accuracy at speed and usually involves shooting while moving, reloading, etc.