I have to agree with what others have said already -
Eagle Arms were always good - very few problems.
I probably had the most problems with Olympic Arms - especially when it came to the rear takedown pin hole and tight magazine wells.
By far the most trouble-free lowers I ever used were PWA - I swear you could just throw it into a bag with all the parts, pins, and springs, shake it up, and dump out a fully assembled, perfectly functioning lower every time.
One brand that seems to be overlooked here is Essential Accessories Co. Back before there were any bans to worry about it was fashionable to turn your nose up at the slightly cheaper, cast EA Co. lowers in favor of a forged Eagle or Olympic. The only problem with this is EA Co. actually built some exceptionally good receivers. I don't think I ever had a problem with an EA Co. lower, and never had one fail or need any fitting whatsoever. But there were times in the 1980's that you almost couldn't give them away, and EA Co. went out of business. I wish now that back then I would've sold my truck and bought 100 of them. If you see a good deal on an EA Co. lower, don't be afraid and just snap it up!