I like the Spikes tactical and Daniel defense LPKs, I bought one DPMS kit and thought the quality was not very good, the trigger and hammer were pretty soft. I have 5 of the Delaware Machinery lowers from RGuns, they seem to be of good quality. Midway puts the DPMS uppers on sale frequently and they seem to be good (Ihave a 20" heavy barrel and a 16" carbine upper from them) I also bought a RRA NM trigger group that I like. What you buy depends on what you want to do with the rifle.