I assume you are asking about their recent offerings (USP and later), and the more common ones at that. I picked up a P2000sk 9mm a few weeks back, and love the way it shoots. It is a V3 DA/SA with a decocker. There are quite a few variants available for the USP line, but not as many for the P2000. For the most part those variants refer to triggers, and the way the controls are laid out. I personally like a good DA/SA gun for the added safety measure, but my wife was not as fond of it and actually prefers the Glock trigger. The DA pull was too heavy for her, but she is very much a new shooter. Her only real experience centers around Kahrs and a 1911, plus the Glock 42 that she fired prior to trying the HK. It isn't a finely tuned trigger, but more than acceptable for self defense. I'm also a fan of manual safeties, and just came across a P30SK with the safety... had I not just purchased the P2000sk, I would have gone with that instead.
LEM is something you should probably check out first, much like a Kahr trigger (not in operation, strictly meaning some like it and some swear off HK for it). I knew going into my purchase that I wanted the DA with an option of SA, so I didn't give the LEM a second look. YMMV.
Those VP9's feel great, but I'm going to hold out for a subcompact version before I jump on that one. Can't really see a need for something that large, especially when I am gonna be moving to California in about 5 months... 10 rounds for me!
I recently held a P99c, and am leaning towards that for my next firearm. I love the trigger in both DA and SA, and the reset feels amazing. It is between that and a Glock 26, but really only for the commonish platform to go with a G42. If you get a chance to rent an HK, go for it. Most ranges I've seen are stocked with those, Glocks, and M&Ps, but I'd love to try a P99. Good luck!