If its my only AR and we are talking a $1k budget, I am probably going with a Colt, Bravo Company, or LMT.
Colt you will find complete.
BCM or LMT you can buy the lower and upper separately, and come in at your price. A couple vendors carry BCM lowers (GR tactical, Rainier are two I know of), and you will be about $400 on the lower, and BCM or those vendors have lots of upper options.
Personally, I would lean toward BCM for the mid-length gas system (and I would go DI vs piston for my only one). If you want a free float hand guard you can go that route, but if you want to KISS with a basic hg, you can do that as well.
On top of the rifle, in the $400-600 range, I would be putting an Aimpoint Pro for an all around (or splurge on one of the Micro's for a bit more), a 1-4x (Vortex Viper PST, Leupold VXR 1.25-4, etc) for a bit of get out there, and if you want to play at the range for paper punching vs "effective hits", then go with a little higher magnification.
FWIW, M4carbine.net is the no BS, no "its just as good as" place to go for AR stuff.