Out of the knives I own, my Brusletto Mora-style fixed blade with roughly 6 inch blade at 1/8 inch thick. This is a great, versatile blade size, thick and heavy enough to do some light chopping but still handles most precision tasks as well as a smaller knife.
I'd pair it with my SAK Pioneer Harvester. Between the chopping capabilities of the Brusletto and the saw on the Pioneer, I'd manage with firewood and shelters pretty easily with little weight to carry. The SAK blades are great small knife blades, good for precision work where the 6 inch blade would feel blundering. Grind the large screwdriver into a chisel and between that and the awl have some extra woodworking tools. The small hookbill style blade makes a nice wood-carving implement too.
If I were to go with any knives out there, I might replace my fixed blade with some larger, like a Busse, Swamp Rat, Ranger or Becker with a blade around 7-9 inches. Something with more heft for chopping type work and a wider blade face for digging etc. That or a good Leukko. In fact a good Luekko / Puukko combination would probably work well too. Pair the larger knife up with again, the SAK.
What the devil would you do with a SAK when what you need is a hard use survival knife. I will never see what you folks see in those flimsy little knives!
Many survival uses are not "hard use" at all. Carving small tools out of wood, notching wood for traps, whittling wood shavings for tinder, cleaning fish, removing splinters, shaping spears and walking sticks - all these are things a SAK would probably do better at than a large chopping style knife like a Busse. This is just using the blade. With a SAK you can also have a saw which has obvious uses, a large flathead screwdriver ground down into a chisel for more woodworking options, tweezers, pliers, small whittling blades, can opener, scissors, etc. They have some of the most efficient raw cutting geometry out of any production knife I've used, so that fact alone makes them hard to be for a small precision cutter. Extreme corrosion reistance and easy to sharpen steel helps in the wild too.