I have used a lot of knives over the years, but for pure practicality most times now I have a Victorinox Hunter for in the field. It has a locking main blade and a gutting blade, so I can open and gut a deer or whatever, and it also has a multiplicity of other uses as it has a really good saw, an awl, screwdriver etc. It is a good size too.
Once I have the animal back to camp I have a knife roll in which I have a Victorinox boner and skinner, steel, and folding gambrel. I think it is had to beat the knives the blokes in the meatworks use, who make a living at this.
I use much the same thing on fish - SAK to gut, Victorinox flexible boner to fillet.
