My best lower as far as fit to all my uppers, triggers that don't need tuning, mags that drop free and a good deep color is a cheap Charles Daly lower I bought before they went out of business. I've got one Noveske lower that no matter how good the trigger was in another gun, it would suck in this lower until it had a 1000 pulls on it or so. The pin holes must be out of line in the slightest way. It's the little things that can get to you...
Want trouble? Wait until the run has started on AR's and parts then buy the cheapest you can find.
If I was building or buying a new gun right now, I'd source a Colt 6720 or buy a Colt lower from Brownells. And I mean Colt, not the Expanse or contracted parts guns.
308 sized guns are a totally different animal and you better do your homework, then play the best odds.
