There are thousands of different AR products and a lot of them are personal preference. Damage Industries makes %80+ of AR parts for suppliers so it's A LOT cheaper to just buy directly from them.
There are two changes that I did to my AR that made a world of difference. One of them is a JP spring buffer and the other is a Geissle trigger. The spring buffer is expensive but goddamn if my AR doesn't shoot like .22 cal rifle now and that annoying rattle/spring noise is gone now. The trigger made my groupings shrink quite a bit. I will also be picking up a JP lightened bolt in the future as well.
Yes, I know you can build an AR a lot cheaper than what I have listed here but I am recommending a solid AR and not some cheap, piece of shit. It also helps to wait for sales and buy pieces at a time. Make sure you research other sites for better pricing. I just used the first website that popped up with the part.
I also prefer to have my lower's to be fully ambidextrous, so there are a couple of repeat parts on here mainly because I need the spring or other part to install the ambi part. I don't recommend the Aero lower, it's what was on my list already because my buddy picked it out. I would definitely recommend something else as I'm not a fan of Aero. On the Ballistic's barrel, it comes with a gas block already. They don't offer the Hanson pencil barrel without it for some reason? I prefer pencil barrels over carbine or bull barrels to save weight and they are perfectly fine as long as you are not firing 100's of rounds per minute out of them. I would recommend the adjustable Syrac Gen II gas block so you can soften the recoil for faster follow up shots (make sure it's the Gen II!).
I would recommend picking up this
VLTOR lower. VLTOR makes
QUALITY stuff and I am thoroughly impressed by my VLTOR upper. It's what I'm going to get for my next complete AR build.
EDIT: Just found this
Palmetto state armory complete lower for $130. Damn that's cheap!
Ballistic Advantage 16" Midlength Barrel
BCM Upper
BCM Charging handle
Spikes Midlength Gas Tube
BCM Bolt Carrier Group
Syrac Adjustable Gas block Gen II
UTG 15" M LOK Rail
SilencerCo Specwar/Omega Muzzle break
Magpul B.A.D. Lever
Geissle Trigger
Magpul Butt stock
Aero Lower
Pistol grip
BAD safety selector
Lower parts kit
Bolt catch kit
Mag release
JP Spring buffer
Trigger Guard
Buffer Tube
Upper parts kit
Troy Ambi Mag release
Feel free to PM if you have any questions. I also have all of the tools to put em together, so if you want to order all of the parts, you can stop by my shop and we'll put her together real quick.