I love AR threads. The AR platform is probably my favorite for training purposes, but they do tend to multiply. I have had good luck with Colt, Bushmaster and Rock River uppers and lowers. I have not used my DPMS enough to comment. I tend to use Bushmaster lower parts kits with exception of a Geissele trigger group here or there.

My most used AR is a Bushmaster A3 16" HBAR upper is an Ameetec lower and a Bushmaster lower parts kit. Below is an old pic of one of the heaviest configurations I ever used in a class. I have verfied that holding this setup in contact ready position with one arm for 5 minutes then addressing a target in 100+ degree heat sucks in case you were wondering.



Over the years, the more I have trained and instructed, the more simple my setups become. On my primary AR, I have a sling, a red dot optic, a light and BUIS. I have gotten away from rail systems due to the weight. DD makes some lighter weight setups, but I could not justify the cost. There may even be some even lighter rail systems now. I don't use a forward grip anymore either. Everyone has different tastes though, especially me as a lefty.

Now I have an opportunity to play around with the .308 AR platform. That means more BUIS, more LaRue QD mounts etc....