I do not own a Colt, but I own a handful of AR's. Some I built, only one that was bought complete. My go to is the DPMS that was purchased as a complete rifle. It's not exactly stock, but it has proven itself to be the most reliable. From what I have heard, read, and experienced, anything DPMS is hit or miss. I guess I got a good one, I wouldn't trade it for a brand new Colt YMMV.
Go here and read the "stickies"
AR Technical Discussion - M4Carbine.net Forums
IMO, the Spikes M4 or Spikes Mid-Length.
ST-15 M4 LE Carbine [STR5025-M4S] - $799.95 : Spikes Tactical
ST-15 Mid-Length LE Carbine [STR5LE2] - $809.95 : Spikes Tactical
They have almost all of the mil-spec features of a Colt, with a substantially smaller price tag. Other rifles in this price range may be good rifles, but they lack some of the standard features of the Spikes (most notably the more-desirable 1:7" barrel twist).
I think I'm going to stick with a S&W M&P 15 AR style rifle...they are basic, simple, reliable, accurate, etc...plus, they have a 5 free magazine deal going on right now.