My search for the best 'survival knife' started back in the mid-late 80s as a young enlisted solider and continues to this day. In the years since I've learned, un-learned, and re-learned what makes a good survival knife, ,or what I like to call a field knife.
For example: Early on I got a Buckmaster, and thought that was bad-***. What I soon found was it just looked bad-***, but cut like crap due to the excessively thick blade and steep grind. Plus, saw-teeth on the spine, , , what was I thinking. Suffice it to say that there were subsequent blades I've had where I've learned what works for me, in terms of ergonomics, weight, size, materials, etc. Ultimately, it's what caused me to start making my own field knives.
Today I think these things make up a good field (excuse me, ,survival) knife: First, ,bigger is not better. blade length of approx 6.5-8 inches long. No thicker than 3/16. Full tang, tapered if possible. Synthetic handle (micarta, G-10, CF, stabilized wood). Good handle ergos. Good reliable and time tested steel (1090, O-1, D2) with appropriate RC/HT for the specific steel. Screwed construction, not simply rivets and epoxy. Satin finish (just my choice in aesthetics). A good reliable, easily accessible sheath that can be carried multiple ways. Jimping on spine and no finger guard on top of handle. And, a nice deep hollow grind, with a stout clip point. And there's more I'm sure that I just can't think of off the top of my head.
Of course these are just my personal preferences. And maybe that's the point. If you are going to find yourself in a field, tactical, combat, survival situation, , , the best knife to have is the one that you feel fits your needs. Better yet, ,one that time has taught you fits your needs. Not one that marketing executives tell you is cool, and/or was designed and 'approved' by any number of special operation / black ops types. The best survival knife is one that helps your most important survival survival tool (your brain) get the job done as efficiently as possible.