Just my 2 cents, but I have carried all three as a duty weapon, and as a former senior firearms instructor.
First choice (very personal) would be a 1911, but hard to get passed a department, even harder to get a modified one through.
I carried a Sig P220 for the first two years my former department authorized semi autos. I never had a failure of any kind with mine (8,000+ rounds through it). Two negatives though, finish wears off rather quickly, and I have seen the trigger return spring break on more then one. Both are easy fixes. A hard chrome, NP3, or gun kote will sole the finish problem, and a yearly spring change out (maintenance) will solve the other.
The USP is the one I have the least experience with, but I never saw one go down, due to weapon failure (shooter error yes!). The finish is excellent. Magazine acquirement can be a pain depending on your political clime and or department. Of the three, it would be the least likely for one weapon on duty and off (at least for me). I had mine permanently put in the coked and lock mode, due to unintentional decoking (thumbs on safety).
I would probably give the nod to the USP my a very narrow margin, but suggest you fire both, and try a few presentations to see which one you prefer.
Regards,
Flyingrhino