1 + with Glock 19926 the "Chart" tells it all.
Some "experts" ding the M&P15 for the few blocks unchecked in THE CHART. I think THE CHART is good to understand what are the differences among mfgs, but also I think entirely too much is made about some of it, such as I am fine with the 1:9 twist barrel as I only shoot 55 grain (it's cheapest, and I don't reload), use fairly short bullets, and don't shoot long range (300 yds or less, usually only 100 yds) and I own a carbine. I think I would be more likely to insist on 1:7 in a rifle. Some will try to make you think anyone who buys a 1:9 twist barrel is, .. "not well informed". Whatever

Everyone gets their opinion.
Now I consider it a fact that there should not even be something called "commercial buffer tube". Please refuse to buy those.
To me THE CHART is NOT the end all be all of AR info that some say it is. But, it is a excellent source when used as one of many. A fantastic starting place.
To me, S&W has all the important things:
- staked gas key & Shot Peened bolt
- chromed chamber and bore.
- M4 feed ramps
- 5.56 chamber = very important, unless you are a .223 only guy who wants the ultimate accuracy, and don't want to fire 5.56.
- They don't have lifetime warranty checked for Smith. I've never has less than exception support for Smith, no matter how old the gun is; so I "double check" this in my little mind. Not only do they have customer support, but it actually works.
-The M16 bolt carrier - they have fully shrouded firing pins. My MP15 looks fully shrouded... maybe I'm not understanding this???? The "heavier bolt to slow cycle time", might be desirable, not sure. It's easy to upgrade the bolt if this bother you.
So is the M&P the end all be all of ARs? Probably not (but some of those are much more expensive). Is it a excellent gun for the money (especially if you get it on sale, remember $100 rebate on all M&P15 till the end of the year) YES. At least I think so.
I really like my S&W M&P15OR. On the other hand when I think of M16's/AR15 I think of Colt. If I had the money, I'd woulds have had to buy a Colt. Will get one someday to put beside the S&W.