I own a USP .45, P2000 9mm, P2000SK, and P7 as well and a P99 and G-17.
I agree with the above posts on the USP's accuracy and should point out it is one tough pistol. The P2K family is great and I like their design over the Glock. I don't really like Glock's trigger system and lack of safety.
The P99 I like is the DA/SA model. No safety but pretty hard for an AD to occur.
Having said all that.
* I think the HK plastic guns are a bit overpriced.
* The P99, USP, P2K are all patterned after the Glock.
* I personally think the P99 and P2K are improvements on the Glock basic design. Or, at least offer you a choice. I am NOT knocking the Glock. I think it has its place. I certainly would not turn one down going to a gun fight.
I personally carry a P7 or a P2KSK.
I was surprised to find the little P2KSk fits me and I shoot pretty good with it (LEM Trigger to boot). I did not like the feel of either the little Glock or little Walther. I don't know about the new Walthers.
I have added the new Walther PPS to my collection. It is pretty much a skinny Glock at 1" wide. It is a great shooter and can easily be concealed. Whatever Walther has done with the design to help with control is great. For a small gun it is really easy to control.