I was looking for an AR recently, as I can't practice with the issued weapons on my own time.
I went with a Colt 6920 from the Individual Officer Purchase Program. If you are a LEO, go to the Colt L.E. website and look around. They have links to distributors that deal in LEO only stuff.
If you're not a LEO, while Colt is the pinnacle, IMHO, there are others that are as good, or almost as good. LMT and CMMG rank up there with Colt from all I've read and people whose opinion I value and trust.
Good luck in your search. Unless you can get a screaming deal on an AR, now is not the time to buy. I'd wait about a year, and buy a bunch of magazines in the meantime, along with ammo. Then, you will find some out of work guy or gal that has to pay his or her bills and will let the AR go for a song.
BikerRN