I've never built one. I nearly have a half dozen times since I bought my first AR15 a Colt HBAR in 1993. I always come up with it's only a hundred bucks more to buy a assembled rifle.
That said PSA seems to make a nice AR!5 for the money. I still have a PSA lower sitting around my brother gave me. A few years ago I researched and decided that Aero Precision lowers were for the money top flight lowers.
Build what you like but a flat top upper with a mid length gas system and a free float handguard with a light weight to medium weight barrel is very versatile rig.
