HK for sure. The HK was built on the .40 platform. Beretta is a good gun too but when it comes to the .40, the HK wins. IMO
I have a USP40 in stainless and it shoots real good. Recoil is very mild and like all HKs, its built like a tank. I don't shoot it that much anymore though because I like shooting 9 and 45 more. But thats just me.
I had a Beretta Elite 92G and it was a good pistol but I just couldn't shoot it too well. Never shot a Beretta in the .40 but from what my friends tell me, its not as good as the 9mm version. I also have a friend who had a Beretta 92 that ran flawlessly, even when dirty or dropped in the dirt. He liked it so much, he went a got a 96 but that one gave him jamming problems. He also didn't like the recoil on it. I let him shoot my USP40 and a few weeks later, he sold the 96 and got the UPS40.
Go with the HK, you won't regret it.
Also, have thought about the Sig 229 in the .40? You might want to give that try too. I bought one not too long ago in the 9mm and it is sweet.
How do you like your USP45C? Love mine. It sleeps on my night stand every night.
Have fun shopping around,
ST