Ive owned a SA XD-40, Sig P226, and now own a HK P2000 .40.
The XD are great pistols for the money, but wasnt a big fan of the grip/trigger safety.
The SIG was the only .45 i have owned and it was great. Never jammed, zero problems.
I just bought the HK. I was looking at USPs myself, but went with the P2000 v2 LEM mainly because i am a lefty and wanted to try something different. I love this pistol.
I would be torn to tell you to get either a sig or HK. They are both excellent.
Have you looked at the p2000sk (compact) and the p30 HK's