I have held all three.
I owned the CGAsh1, and have butchered an elk with it, and used it hiking and camping.
The grip is fantastic for combat. In the sense that you can stab and pound with a very secure feeling. It is less ideal for extended chopping and other tasts.
The Sar6 has a giant handle, with room to move your hand forward or backward as the need strikes you. The handle is weighty. It would make a great general camp knife.
Don't discount the Boss Jack either. They are awesome in the hand. Shorter blade height from edge to spine may make for a better design for getting up in the elk etc.
What you will give up with the Boss Jack is overall chopping ability when compared to the SAR6. Still an awesome knife, and is indeed a great general purpose knife from a camp chore stand point. You can get the .22 CG or the LE with the skinny blade.
Either will be an instant classic! I love the original, but I have to say that the new Boss version is actually better! The grip is better, with a bit more height in the handle where the pointer finger goes. The CG, especially can't be beat from a price point consideration.
Not mentioned in your list, is the SarQ. A great general camp knife. Not too thick, not too thin, chops great for it's size. It may be a bit long for actually gutting, But I think it is manageable. One of my favorite mid size Busse. The only thing I could ask for to improve on it, would be a slightly taller blade height (just so the talon hole was not below the edge for use on the cutting board.