Heres my humble opinion. First, it should be something you carry and use all the time. Don't wait for a survival situation to learn your Knife.
The knife should feel like an extension of your hand.
Real world situations you may be faced with in your daily life:
Cutting seatbelt at car accident to remove injured person from vehicle
Fending off a neighborhood pitbull or other aggresive dog
Defending against a thief/mugger or anyone else you may mean you harm
Classic survival situations:
sharpening fishing spear
cutting rope, clothing, bandages,
Defense against animal
Defense or Offense against Human
Based on these, I think an ideal Survival Knife should:
Be a locking folder 3 1/2 to 4 in. blade length for ease of carry.
Have a partially serrated edge for rope/cloth cutting.
Have high quality steel blade (Skinning a deer with a cheap blade means resharpening often).
Have an aggressive point and proper handle for defense purposes.
Here's my submission for Best Survival Knife
It's the best knife I've had. I grew up on a farm, was a combat Marine, (not an office pogue), boxed and currently do MMA and have a machine shop
in my garage so I have a pretty decent background to judge survival/combat knives. Still, it's just my opinion.
Last thing I'll say about the knife: Because of the steel reinforced nylon handle, it's actually a well balanced knife. Meaning you can throw it,
very rare for a folding knife. I've had this type knife for 9 years and can draw and throw it up to 10 feet as quick and reliable as a cop can draw
and shoot (better than some). Nice feature if you're in a store getting robbed.