My Mutt Vic. I waited two days to post my answer,like Roo I had to think about it for a bit. You insist it may only be one knife. So thought was needed. I carry a minimum of 4 every day. Hip,front left,front right and a necker. I load up when I am in one of my 5 pairs of cargo pants, using the extra 3 pockets as concealed carry lounges for my folders.
The Mutt is a pry bar of a knife.
It is SOOOOOO frickin thick that it can handle any chopping situation as well as be tied to a stick for a spear. Mine is so sharp it slices tomato's with glee of course.It is deft enough at the tip to cut easily around bones,vertebrae and clean fish with ease.
My Mutt is a tank of a fixed blade and I choose it.