I voted LMT and DD because I actually have an LMT rifle and a Shrubmaster with a DD barrel on it. For those voting for the best, be careful on what makes the AR really good.
Do we go with the brand that offers several platforms? Reliability? Price? Customer service? Accuracy? Example I don't have the priviledge of owning a Knights Armament but what if a part like the BCG get damaged? I heard they are NOT interchangeable with the other brands of BCG's.
Money wise, DD and LMT are superb for its value. Actually come to think of it, I was about to make a topic where is there a point where these companies make AR's to such a degree that it doesn't really matter because the quality is already at the highest?
Example would be if you were not told what the AR you had in your hands, and as long as it shoots, doesn't jam and was really reliable not to mention the stock AR had an excellent fit and finish, does it really matter? Beyond the pricing of the LMT's and DD's, is it really just buying for the name? Ok OK I know that the piston AR's have always costed a little more....
You really do get what you pay for. Just remember that Ferrari's and Lambo's are not only fast but repairs are terribly slow when you need parts. Same applies here for AR's.