Howdy!
The HK has the advantage of out-of-the-box reliability, whereas most 1911's will require a bit of tuning. (And some require a LOT of work in order to be street ready). The USP is the most accurate stock pistol that I've ever fired - amazingly so, in fact.
However, I do not own one, and doubt that I ever will. Why? Because it is a beast to conceal. In one of my Max-Con V's, I can effectively and comfortably conceal a 5" 1911 while wearing cargo shorts and a tee shirt. With heavier clothing, it is that much easier. Rule #1 of gunfighting is to have a gun. If I cannot conceal it, I cannot carry it on my person. If I cannot carry it on my person, it is not going to fulfill rule # 1. It then becomes just another expensive toy.
As a side note, if you want a truly great street pistol on a budget, look around for a Norinco 1911. The quality of the metal and heat treat is heads above any current production 1911 (They are entirely forged, milled and hand fitted - just like the Colts were several decades back). I've NEVER experienced a malf of any kind with one, even straight out of the box. All you absolutely have to do to one is put some decent sights on it, and replace the mags w/ metalforms or Wilsons and you're set. Then you'll have some $ left over to take a tactical handgun course from a good trainer and you'll be worlds ahead of the guy who buys an expensive blastomatic and pronounces himself "ready". (I had already fired thousands upon thousands of rounds before I ever set foot in my first professional pistol course. Within about 20 minutes I realized that I was totally clueless in real world defensive shooting.) Training/skill/mindset are way more important than what equipment you choose. I hope this helps you. Please feel free to contact me if I can be of any further assistance. Thanks!