Feathered Friends, Western Mountaineering
You want baffle box construction, not sewn through, for better warmth.
One I just became aware of on top of those two is the MontBell Alpine Down Parka, not the light, the normal Alpine down parka, it's baffle construction, a hefty 7.1oz fill and only $330. This may very well be "great deal" winner, and it may not be a close race, I can't find anything that'll compete.
Feathered Friends and Western Mountaineering have jackets that'll cover going to get your mail to climbing Everest in the worst blizzard ever seen. These don't tend to be cheap but I don't know that I'd say they're inappropriate, especially given where and how they're made.
First Lite doesn't give you proper rating of their garment, we know First Lite does China, so, no. I'm sure it's "fair enough" but for the price, just no, no point.
Stone Glacier does give a proper rating, but 5oz loses to the MontBell and it's sewn through, which really loses.
I could care less about kuiu but I believe you've got to go to their Super Down Burner before you hit baffle box construction, does appear to have a decent fill weight, is very expensive and therefore I'd be going Western Mountaineering and supporting America or Feathered Friends with far more America friendly construction, better for similar cost, probably less, depending.
The Super Down Burner does seem like it'd have the most durable outer layer, the companies I listed initially do have varying degrees of durable down jackets but I don't believe they hit this level. However, kuiu doesn't give a total weight, so I'm guessing this durable outer is going to be heavy, which tends to be a double-edged sword.
Generally, with a down jacket they are light and tend to be fairly fragile, but the point is extreme packability and extreme light weight for warmth level, with the idea that you're throwing some form of outer layer over it when needed.
They aren't really meant to be "the" outer layer, and there's multiple reasons for this, but really the obvious Trump card just being that a person isn't generally going to want to be sweating their nuggets off busting brush and doing intensive hiking with a puffy on like these.
You'd generally pull these off to get after putting on miles and busting brush/climbing steep slopes.
Then you put these on when glassing, chilling back at camp, sitting and calling etc...
Now if you don't need warmth... well, get whatever, but even if it isn't going to be 20 below zero, but 20 or 30 above with heavy wind because you're on a mountain, it would lead me right to going with what I noted. I'd err on the side of too warm vs. too cold, personally.
I've got some Western Mountaineering gear, it's good stuff, I think I might buy one of those MontBell to try and see what they're about, you sent me down a path I didn't need to traverse, though I do have a ton of down gear, what's one more thing.