Hey there hound!
I have done about 6 months of research, and these were the finalists for me:
HK USP .40, Glock 23, Sig P229, and SigPro SP2340.
First, about the HK's. They are dependable, super reliable, and the cocked and locked feature with integrated decocker is great. But I found it to be quite big and bulky (Very bulky) and was not as smooth ergonimically as say a P229. Not by a longshot.
The Glock, the grip angle is a big excessive. That makes for a bad wrist angle, and thus increases muzzle climb, when your wrist will fight to return to it's natural position.
The Sig P229, SWEET. That's all I can say about it. MUCH smoother trigger, and the most ergonomically correct gun of the bunch.
The Sig Pro 2340 is pretty cool. Everything on it is a bit more heavy duty than the P229. The polymer meant cheaper $$$ and less felt recoil vs. the P229. Integrated decocking lever is also in a snag free design. And because it's a sig, you know it's ergonimically correct and gives you a "tactile" feel as your bullet leaves the chamber that you don't get from other brands of guns. Have you driven a BMW or an Audi or a Porsche? You know the "feel" that is so distinctly German that you can't describe, but Honda tried to capture but didn't? Well, that's the same thing with the Sig's. There's a "feel"that you get from the Sig's you can't get from other guns.
So my pick was the SigPro 2340.
Keep in mind though, Sig, Glock, HK, there is no "BAD" gun in the group, just personal preference.
A little bit to keep an eye out for, I was looking at .40's I don't know what caliber you are looking at. But I was a bit hesitant about the Glocks because their .40's aren't fully supported barrels and I fear Kb! Before Glock people start bashing me, if you don't feel it a diet of reloads and +p+ stuff, there should be no worries.
Shoot safe, and let us know what you get.
Albert