I would look for a folder which has at least 3,5 inches of blade, preferbly ffg, handle material is not that important but how the handle fills my hand is more important.
It should be a handle that fills my hand well so that I do not have to have a tight or clenched grip, it should not produce hot spots when working bare handed. The knife might be the only tool to help produce some kind of shelter or kindling for fire and getting blisters in your hands after five minutes of work in a survival situation is bad.
A good carbon steel would be nice, since you can pick up flint and get a spark of the back of the blade. I would like a steel that keeps its edge, is easy to sharpen, decently rust resistant VG-10, S30v, 154CM, perhaps even the 8CR13MOV tough it is in lower quality than the others.
The back of the blade should be decently smooth close to the handle and have a more square edge close to the tip, this is to help saving my fingers if I use a choke up on the blade, I have noticed that my RAT-1 shaved skin of my thumb before I rounded of the back of the blade. The square part is to help with throwing sparks from a ferro rod. Perhaps the inside of the spydiehole could help with this as well.
The spydie hole could perhaps be used as a pivot for a firedrill. Just a thought.
In Spydercos lineup I would chose between a Stretch 2 with FRN handles, Military, Paramilitary 2 perhaps Endura or Tenatious
I have a manix 2 which is a great knife tough I find the jimping on the "inside" being too agressive and I think that the jimping on the top will be as well and create blisters.