If you were in a 72 hr+ off grid survival scenario what one knife would you trust to fill the role of a survival knife? To make kindling, to prepare food, make a spear, make a shelter or to battle a zombie (just kidding with that last part). I personally would trust the TOPS silent hero. Looking forward to hearing your feedback!
Probably whatever slipjoint(s) I have on me.
As for "making kindling" when out camping, to be honest, I always found enough twigs and dried leaves for kindling, and a old dry stick for whittlin' a feather stick, when necessary at the camp site. Usually right where I wanted to pitch my tent.

"Making a spear" ... are you talking a pointed stick spear, or lash the knife to a stick as the spear blade?
For the latter, something like my Cold Steel "Bushman" (not the bowie version) or some other hollow handle knife would be "ideal". Of course the chances of having it on me are less than slim to none. I haven't seen it (or my GI Tanto, and the three CS Kukri machete I have is seven years or so. It's in another state, anyway.) The only fixed blades I have access to right now are a Mora N°1, a Cold Steel FINN BEAR, , and Toferner neck knife. The Toferner wouldn't be much use as a spear point; the blade is under 2 inches. Even if I had one or both of the other fixed blades with me, I doubt I would tie one onto a stick to make a spear, anyway. Carve/whittle a suitable stick to a point, and fire temper the point, will make a spear plenty good enough for fishing the shallows. I wouldn' use a spear for game. A snare or other trap might be more efficient than hunting with a spear, and don't need me there to get the critter, allowing me to do something else that is productive. A slipjoint pocket knife can whittle/carve a trap and snare trigger.
I can (and do) do food prep with any knife I have on me.
I believe the stockman or Barlow along with a Scout Knife or SAK is quite capable of doing everything I need to do "in an unexpected survival situation, including making a shelter, provided the materials for a shelter are available.