My build.....AR build anyways.

Agreed, the M&P15 (for instance) has stellar reviews, it is extremely durable, very good accuracy point, so for the money, I see it as a win/win. Not everyone has thousands of dollars to toss out on an expensive rifle.

I bought one to test out and I see absolutely nothing wrong with it. Functions flawlessly, accurate out to 200yds easily.
The M&P is a decent carbine. S&W is a big name and they have some pretty good processes in place. The only issue I take with the M&P carbines is that I often see parts built in a 'cheaper' way than the std gov part. The thing they've gotten right is that their guns are still compatible with the gov style parts in most cases.