If you don't plan on hunting, then it is hard to beat 556, and I have seen lot of deer taken with 223, so that might not even matter. Honestly, I would say daniel defense, mid length, your choice of Aimpoint, Eotech, or Trijicon. With your set limit it should be really easy to make you happy. The Colt is what I decided on, but if I had the extra money, I would have went DD, or BCM, hands down. As far as AR brands that are safe, nowadays, most of them are. Go DD, BCM, Colt, BM, Armalite, and you will be ok. Have fun with the build.
Also, there are brands like LMT, and Larue that will fit in your price range, and really give you something special. The PredatAR is incredible. But they are pricey, and all you are getting is a cooler looking slightly more accurate(debated) rifle.