For about 90% of the people reading this thread, myself included, any single knife regardless of the length or width or weight is going to be outpaced by our lack of survival skills...unless it is a hollow handled survival knife with a fully charged satellite phone jammed in the cavity where fishing line is generally stored.
The premise is flawed: setting out on purpose with just know knife to do it all but leaving behind invaluable tools like a hatchet? IF I were going out on my own with only one edged tool, I may very well pick a nice hatchet over a small knife or a large knife if forced to choose. I can do a lot of the cutting jobs a small knife can do with a good sharp axe yet still process wood and split animal carcasses if the weird need arises.
So given the ill-advised perimeters, I would elect to bring a thin stock khukuri. 15" overall length sporting about 10" of blade. Weighing about 15oz. So, under a pound, easy to sharpen steel, good chopping ability, useful for finer work if you have been handling them for a couple of decades like i have. No frills but a solid jack of all trade tool.
That said, if I were in a plane crash with nothing more than my 3.75" Fiddleback Monarch, I know that my survival skills could mostly be augmented with just that little fixed blade. I could make a fire and press it into making some sort of emergency shelter. I could process what little food I could scrounge, and give enough time and smashed fingers I could figure out how to set a dead fall or a snare.
In short, I would be well dead before I ran out of blade using just the 3.75" or died from exhaustion trying to hump it 30 miles with the mentioned 3lb knife that weighs more than my 40+" Scottish Claymore. No one that stumbled across my cleanly picked bones would tisk and shake their head, "If only he had carried more/less knife...: