Coal Dragger
member
OK, for home and property defense I'm going to work with the assumption that we're talking about a duty grade fighting rifle. So with that in mind, I'm going to suggest that with a budget of $1K max that you look for a Colt LE6920 or LE6720.
Now many are going to push back on this suggestion. The most common arguments against the Colt will be: that you're paying too much money for just the name, or some lame nonsense about mil spec being lowest bidder garbage.
I reject most of that reasoning. Now you will pay a bit of a premium for the Colt name at least in theory, but you are getting a properly assembled rifle with a lifetime warranty for that money. The lowest bidder argument is a load of horse doo-doo, the US gov't has a technical data package specifying materials, dimensions, and manufacuring methods. As the largest single user of the M4 pattern rifle they actually have a pretty damn good idea of what it takes to get a highly functional and durable carbine for a reasonable price.
If you compare the specs, materials, materials testing, and manufacturing techinques with more budget oriented rifles you're going to see the Colt generally is better made, and they are consistent. Compared to some more expensive rifles the Colt features and materials represent a very good value.
If you can swing a bit more $$$ a basic BCM or Daniel Defense might be worth a look. For that matter the new Colt Combat Unit looks freaking awesome but is going to be a bit more than $1K although it will have a mid length gas system, and very high quality Centurion Arms free float rail.
In the end an AR is essentially a barrel, a bolt, bolt carrier, and a trigger. The Colt will deliver a barrel made from CMV 4150 (machinegun rated) steel that is chrome lined, high pressure (HP) tested, and magnetic particle (MP) inspected. You're also going to get a bolt made from Carpenter 158 steel, HP and MP tested, and shot peened with a good tool steel extractor. The bolt carrier will have a properly staked gas key and chrome lined interior. The trigger will be GI spec, nothing to write home about admittedly.
Oh well, there's my $.02...