To begin, most commercial ARs in the price range you specified are built to Mil-Spec tolerances and expectations. As a result, they are more alike than distinctive. Aside from fit, finish and extras (grips, rails, gas system lengths, receiver set-ups, etc, etc), your decision should be based off of value and customer service, not necessarily a fancy name or laser-etched logo on the receiver.
That said, specific requirements are necessary to accomplish match grade accuracy. If you're not planning on plugging varmints past 200 yards or shooting match with the weapon, an all purpose rifle is your best bet.
For that purpose, it's hard to beat a 16" barrel. They are maneuverable, light and more accurate than many would have you believe. For a nominal price increase, you should go with the chrome lined option as it extends barrel life and durability. I would recommend 1:9 twist as it was designed specifically to stabilize the widest range of ammunition, perfect for a plinking/SHTF combination rifle.
The Wylde chamber is more costly than it's truly worth, and I suggest you get a weapon rated at 5.56 NATO. It will shoot .223 with no problems, but can support the higher pressures of the military cartridge. I prefer a flat top A4 upper. If you plan on using any sort of optic, this feature is invaluable. Furthermore, detachable iron sights and carry handles are available at nominal cost, leaving you the option to switch out as you see fit. Mounting optics on top of an existing handle leaves most shooters struggling for the appropriate cheek weld to the stock.
Stag Arms, Rock River, S&W, and DPMS all have proven track records and are all brands that I might suggest. I prefer RR, as they come standard with a two-stage trigger, Hogue pistol grip and offer multiple configurations for you to choose directly from the factory. Bushmaster has more supporters than it ought to, especially with what it's done to the ACR. Most people "in the know" don't buy them, and for good reason.