I know almost nothing about AKs so can’t help there but for budget minded ARs I would say either a S&W MP(they have several models under 700) or an Olympic Arms. One of mine is an Olympic with 16″ bull barrel. Took it on a prairie dog shoot and ran about 500 rounds through it in 2 days without cleaning it. Never had a hiccup. Some people don’t like them but it has been a great gun for $650.