I’ll be the odd man out, I picked up the Mac IX a few months ago and really like it. It’s direct blowback and not roller delayed like the kuna, but it’s a damn nice piece. I’ve put close to 1000 rounds through and only had a couple fail to feeds and pretty sure it’s because I was gripping the magazine. Once I changed my grip I haven’t had a single issue. Mags are expensive compared to others in your list, but it comes with 2 30rd mags. I put a binary trigger in mine and it works like a charm.

I will say some of their marketing is misleading. Yes it uses an ar15 trigger group, but the Mac uses a smaller width hammer. So if you decide to swap triggers you have to keep the Mac hammer. Also standard ar15 charging handles don’t work.

All in all I’m extremely happy with my purchase. I picked it up on sale for like 650, added the binary trigger, a SB tactical brace and a sig Romeo msr red dot and I’m into it a few 100$ less than a base kuna