There can be many answers here. If you plan to spend 1K on a AR15, then your best bang for your buck would prob be a Colt6920. But you do not necessarily have to spend that kind of money to have a nice rifle. There are other AR15 options out there for $500-$700 that are great rifles.
Here is a link to a Bushmaster AR15 that you could get for $449 that has a flat top to put a optic on.
http://www.bayoushooter.com/forums/...t-30-Rnd-449-after-50-MIR-(FREE-S-H-over-500)
DPMS, Bushmaster, PSA, S&W, Stag Arms, DD, Ruger, Rock River Arms, Colt are all good. Go with a 5.56 chamber spec model as a suggestion. Are you going to be walking to hunt them or from a stand? Do you want tactical as well? Do you want a match trigger or std trigger? Do you want std furniture or tactical? Flat top with backup irons? Fixed or Magpul stock? You could build your own but be advised you will then need to join a support group for ar builder rehab:}