Here you go: This quiz will help you decide if you really want an H&K
1. Do I want a hammer fired carry pistol?
NO - get a Glock, XD, S&W M&P, Walther
YES - go to next question
2. Do I want an all metal hammer fired pistol?
ALL METAL - get a 1911, SIG, Beretta, CZ, 3rd GEN Smith
NO, I WANT POLYMER - Congrats! You want an H&K
Decide on model and whether you want the DA/SA, SA, or LEM trigger system. A bit tongue in cheek, but true.
The USPc carries about the same as a G19. Perhaps just a little easier. Especially if you are running LEM with no control lever. If you can routinely carry a G19 size pistol you will have no problem physically carrying the USPc. You will just have to decide if you like the type of trigger actions available to you. I like LEM.
If you can swing it, I suggest you purchase the H&K and keep your Glock. if it turns out you don't like the H&K after all, you still have your G19 and keep the USPc for range use or sell it or trade it out.