Which one?
 

I'm a long time bolt gun guy that's pondering an AR due to today's low prices. It'll be for plinking and home / self defense. Prefer a finished gun, no desire to "build" one. I want it to be a carbine with open sights in the under $700 range. School me on the differences, advantages, disadvantages of all the brands (S&W, DPMS, Core, DelTon, Ruger, Windham...........). As of now, the S&W Sport at about $600 looks pretty good to me.

That's the nice thing about "mil-spec" built AR-15's.

Some time down the road you can swap-out any part you want !!!


Buy one with a history, and one that stands behind their products.

they are all about the same, they all buy parts from the same pool of parts vendors (with a couple exceptions that make parts and build their own) and just put them together, the main differences are the quality of barrels and the warranty.
RR