The Glock and M&P line of pistols are "OK" in my opinion but not my first choice.
That's just me and over twenty years of carring a gun talking so take it for what it's worth. If the agency you are employed by issues the M&P I would seriously look at that line over the Glock. With that said, if I had to choose just one it would probably be the Glock if employment wasn't a factor for the availability of spare parts, magazines, etc, etc.
The Glock and M&P can make good home defense weapons, although I prefer a longarm in that role unless going to see what made that "bump in the night". If I know it's an intruder then it's time for the longarm and the handgun becomes the back up weapon. I am of the opinion that not all handguns are created equal and each platform has it's pros and cons. There is no one gun for all situations.
I'm willing to bet that you will shoot the M&P better due to the ability to change the backstrap to get a better fit with your hand. That's a big plus in my opinion. Shoot both and see which one you do better with and try the different backstraps too. You might find one that gives noticable improvement. Just remember that just because your employer issues the M&P today doesn't mean that it will be in your holster tomorrow.