VERY different pistols....
Glock: Single-action only--kinda, no external safeties (ok the safe-action thing but you know what I mean)
HK: DA/SA, can be carried cocked & locked.
The main difference is do you want to pull trigger go bang, or do you want something with a dingus on the frame? I liked the dingus because I shot it enough to sweep it off, every time and I liked the idea of cocked and locked tupperware. But 10-ring shoots his with the DA pull on the first shot. If that were the case I'd send it in for the LEM modification and get rid of the decocker. I see guys at IDPA matches that get their USPs and forget to click the safety off. Main thing is, if you're not going to use the safety, will it be a liability for you? If so, I'd lean on the Glock.
If you want the HK but want a pull trigger go bang type of action, send it in for the LEM which costs, $96 I hear.
JMO