FF and WM are great bags. I think Stone Glacier offers some elements that those two don’t especially if you are a tall or wide torso/shoulder person.
SG foot box just sort of floats over your feet and does not push on them. Never found another bag that does that. Once you try or feel what I am describing you won’t go back. I have size 15 feet so that is important to me.
SG has differential cut so even if you push on the inside you are not compressing down.
SG has an excellent size and shape that accommodates wide shoulders and back sleepers with elbows resting at sides. I use the 25” wide exped tapered pad and my elbows are just on the pad but not pushing on the bag at all. Not restrictive through the hips or legs.
Huge loft on the SG.
Only other bags to maybe look at are Sitka (features like arm holes and center zip), or KUIU but I think the SG Chilkoot is too good for my needs to consider the KUIU. Argali doesn’t check any boxes to make me consider them but a lot of people really like the Argali.