I could never find a Glock that fit well and pointed naturally which to me is important if you ever had to point shoot. Sure, you can train, but I'd rather work with something that's natural feeling.
At any rate, I have an XD9SC and an M&P9C. The XD has roughly 800 without any failures of any kind. I've never had to give the grip safety any thought in either strong or weak hand as it always disengaged for me.
The ergonomics on the XD is better than that of the M&P, IMHO. The XD grip fills my hand better and I have medium hands. What the M&P has over the XD is the thumb safety which I prefer, but may be an non-issue for you. I do like the finish and SS internal parts of the M&P, though.