Don't own a M&P AR15 but I do own a few other brands. Like my signature says "Use should dictate gear!" I voted Red Dot because that is what is on the majority of my AR15s but I also have other optics.
For defense guns that will be used to protect myself and my family Aimpoint Red Dots are my choice. I like the H2/T2 if you have the coin or a Aimpoint Pro on the budget end. Red dots are excellent for spitting distance to 200 yards for me. They are fast to target and accurate enough. I can easily shoot minute of man with Aimpoints and I cannot see a situation where I am engaging beyond that. I mainly use these on 14.5" and 16" guns. If I had to choose only one it would be a Aimpoint T2.
I also run a few 1x6 variable scopes on quick detach mounts. These days that means a Primary Arms 1x6 on a American Defense mount. I like this setup for something that can push out to 300 with the ability to tighten groups if I am up to it. I use this on a 18" build.
I am also looking or an ACOG in 2017 to use on a Colt 6920.
In the end you have to look at what you want to do with the rifle. What your vision is capable of and of course your budget.