You'll find opinions on safeties all over the map. To further confuse things the M&P is offered with options for safety features that are also all over the map. You can get an M&P with a thumb safety like a 1911, you can get them with a magazine safety or without, finally they all come with that silly flipper trigger that just bugs me. BTW, the reason that flipper trigger bugs me is that if you have skinny fingers and grab the trigger high, you won't be able to pull it.

Personally I started out shooting revolvers and prefer my guns to not have any safeties that I would have to remember to turn off. It happens that I have a striker fired semi, but it was chosen partly due to it's featuring a passive grip safety. However, my Springfield XDm is a range gun only and I wouldn't consider carrying it, IMO the trigger is just too light. I like to carry guns with what many consider to have a heavy DA trigger, which in my case is Sig Sauer. However, Sigs with the DA/SA trigger set are distinctly right handed, so my vote would go to the H&K if you intend to carry. If it's purely for range use, the M&P is a fine gun at a much more affordable price as long as you can adapt to that silly trigger.

Finally, I would advise you spend some funds on renting any of your potential choices at a range that offers rentals and try them out. Finding a handgun that fits YOUR HAND isn't something you can learn by reading about them, you actually have to try them out. By renting you avoid making the mistake of purchasing a gun that isn't a good fit and later selling it at a loss.