I second the previous comments touting BCM. I too had a hard time deciding on AR-15s recently and looked all around and for their reputation and price, the BCM complete uppers was something I was going to go with. I was looking at a BCM Mid Length Upper with just the standard A2 front sight post and was going to pick up a lower locally. Wasn't going to go crazy with match grade triggers or anything of that sort. Single stage Mil-Spec is fine for me and my intended use as a defensive gun, although my primary home defense gun is a Mossberg 500 Thunder Ranch.
However, found a Colt 6721 at the $900.00 mark and just added the aftermarket Magpul furniture and recently changed the stock to a BCM Mod 0, which is one of the more sturdy collapsible stocks out there for less than 60.00, and lastly a Raptor Ambi Charging handle.
No optics yet, thinking about investing in an Aimpoint PRO or looking at a more economical and fairly tough Primary Arms Advanced Micro Dot, but I swapped out the Magpul Mbus for a fixed DD rear sight while there is no optic and will switch back once I do decide on an optic.
$$$$ is a big factor to me and altogether I believe I put in about $1,250.00 on this rifle after the aftermarket "parts" but keeping the OEM BCG and trigger and again it does what I need it to. No plans to shoot competitively at all and I have about 800 rounds through it since owning it in December.
DD is a fine rifle, but if you can get a Colt and make modest upgrades you can save some cash OR definitely look at supporting BCM. Their KMR hand guards feel fantastic and their patented cross bolt lockup at the barrel nut might be one of the most secure systems today.