When I'm backpacking, I carry the Leatherman Squirt PS4 for the combination of pliers and scissors. The pliers get used to drive a heavy needle for gear repairs in the field. Just used them on the last trip to remove (screw driver), repair (pliers and scissors) and reinstall a blown wrist strap on my hiking poles. The scissors also get used for first aid and nails as others have described.
If cutting tasks were nothing more than than thread and foil packaging, this would be all that is needed. But for us, food often means meat and cheese or peanut butter. Not adverse to starting a fire if wood and local conditions allow. I find the Opinel 8 or 9 is great at both and carries well in the pocket.
I've heard this discussion quite a bit in backpacker/hunter circles. I find that the longer the trip - the larger the knife I need. If I'm car camping overnight and fishing then I bring the Leatherman Wave with me. I use the pliers, wire cutters, & scissors. If I'm out for a week or more in the "back country" then I carry the Ontario Rat 7 with a serrated blade. It's good for cleaning animals, chopping sticks, and splitting wood.
I carry a Gerber Dime as my everyday carry multitool because it is very light and has almost always been enough to do the chores I would call upon a tool for. I recently damaged one of mine using it to pick up something that would not weigh quite as much as my backpacking pot so I know I can't count on it to lift a hot pot. I take with me the Leatherman Wingman on the few hiking/camping trips I have attended. It gives me much more durability and utility while not bearing the weight or cost of many of their nicer tools. It weighs slightly more than my larger folding knives but has scissors, knife blade, and saw, all of which I used on the last trip, as well as the pliers which I can almost always make use of when I have the thing on me...
I always have a fixed blade on me, I wouldn't go anywhere without it. Who knows what trouble you might get into in the wilds. It's always good to have for protection as we'll, if you can find a nice lightweight knife it might be worth it. I usually carry a Remington fast on me. On the other hand it's always useful to have a multitool maybe if you could also find a lightweight multi you could pack that as we'll.