Try asking the same question on the HK Forum and you might get some different answers...
I have several 1911s and several HKs. Both have their purpose. I perform best with the 1911, but I still love my USP45. I have the match trigger installed along with a weaponlight. The USP is probably the best choice if you are looking for reliability, performance, and the ability to accept modular lasers/lights/etc., on a budget. That is not to say the 1911 is not capable of the same thing; it will just cost a bit more to get it to perform to its potential.
As far as accuracy, the stock USP is capable of 3-4" groups at 25 yards. Drop in a Bar-Sto barrel and this will decrease to 1.5-2" groups. The USP does not have MIM parts like the Kimber, and the USP's out of the box reliability is typically better than the Kimber's. YMMV. Just make sure you have big enough hands to handle the USP.
Tim