I love both my USP45 and HK45 equally. I did have a uspc 40 at one time and I loved that also. But I am going to buy an HK45c here soon. I feel it is pretty much a USPC but more streamlined. I also like the refinements made to the HK45/c's the sight radius is better, the stock trigger is better, the mag releases are better, and the overall feel is better. That is not to say that the USP isn't amazing, just different.
My go to gun for huge problems or SHTF for those of you that like that term, is my USP. But I EDC my Hk45 everyday when I am in the states. Plus if the HK45c is good enough for the SEALS it has to be good enough for me. They are both great pistols, it is not an easy decision, and in reality you can only carry 1-2 of them. A nice secondary/tertiary combo would be the HK45 and HK45c if you run like that.