I have used and owned them all. WM, FF, SG chilkoot 15, and now Argali Alpine 20. Chilkoot 15 was one of my favorite bags. However, I am only 5-9" and the chilkoot only comes in long size. No point in heating up wasted space.
I would say the Argali Alpine bag is on par with WM and FF. It's the only hunting brand that meets or maybe even exceeds WM and FF. Brad is using only the best material in this bag. I would rather support a small cottage hunting brand than a non-hunting brand that is sewn with foreign materials in the US. Also, the chilkoot uses treated down which I have personally done real world testing and find regular non-treated down to be superior. Treated down flat out does not loft as well as non-treated down and you cannot argue it. Loft is how you achieve warmth.