Most companies that sell AR15s don't make anything.They assemble guns from parts from outside vendors,the AR15 industry is a "house of leggo".They are buying alot of their parts from the same sources.
The AR15 by which all others are compared to is Colt.While Colt doesn't make as many components in house as they used to they use quality vendors like Continental Machine Tool,Creed Monarch,and others.
Lower forged receivers are primarily made by 4 manufacturers for the industry,CMT,LMT,LAR,MMS.The major difference between them is logos,markings and color,forge flashing.
If you don't want to pay prancing pony prices but want the quality build your own.
I recommend for Tier 1 parts:
BCM uppers
BCM bolts and bolt carrier groups.
BCM has CMT charging handles,same supplier to Colt.
BCM Colt M4 stocks
G&R tactical lower fire control parts set.
Forged lower of your choice,DPMS,Stag,RRA,Armalite,Bushmaster,Barrett,they are all the same.Choose the logo and markings you like and match for color.
Add BUIS of your choice from vendors like ARMS,GG&G,MWI,etc.
Stocks from MagPul,Vltor,etc with mil-spec receiver extensions.
The kits from the bigger AR15 vendors are fine for "hobby level" AR15s.
***Avoid anything Hesse,Vulcan,Blackthorne***
http://www.bravocompanyusa.com/
http://www.gandrtactical.com/