The M6 is a beast. Heavy and very stout. I would go with the S6 or JackHammer over the M6 based on blade to weight ratio.

I have both the Chopweiler and the Sarsquatch and I prefer the shape/feel of the Chopweiler and the steel of the SarQ. I like the SFNO even more. My two top camp knives are the Camp Tramp and the SFNO.