I have a small hoard of Busse Knives. The largest in my collection (SFNO) has a 7 inch blade. The smallest (game warden) has a 3" blade. Of all of them, the most used are the game warden and a SAR5. The second has been almost entirely scrubbed from the collective memory of the Busse faithful, but it is what I was looking for, though I didn't know it at the time- and I haven't bought a fixed blade knife since. I have 2, one is factory fresh, the other has been stripped and polished. Of all of the knives that I own, if someone were to say "okay, you've got a no-shit SHTF scenario, what knife do you want?" it is the Sar5. Strong enough to baton through anything you'll likely encounter for firewood. Thin enough to slice. Not light, but light enough to carry all day while carrying a rifle and a pack through the mountains. No giant choil taking up valuable blade space. I don't care what you say about a "finger coil," a real handle is more comfortable to hold than the bare blade steel. It's the most efficient usage of blade edge and handle length that Busse has ever made. And, they immediately discontinued it. Jerry Busse said he thought the handle felt like a hammer handle. Yeah, I guess it does. No weird swells. No skull crusher pommel. No hot spots from continuous usage. And, it doesn't resemble a scotch tape dispenser.
View attachment 7318341
Anyway, you probably can't find a SAR5 today, and if you can, it will be expensive(ish). But, I'd lean towards a 5" blade, 1/8" to maybe 3/16" thick. No choil. Drop the blade edge below the bottom edge of the handle so it doubles as a guard (you're hand won't likely slip over the blade because the blade has a greater depth than the handle). There are a bunch of great steels, and I'm not going to fanboy any. Pick one. G10 and micarta are strong, but heavy- and G10 may prove brittle. Stacked leather is super comfortable to use. So are wood handles, typically.
The above doesn't really answer your question. But, a survival knife is the knife that you have in you possession when you find yourself in a survival situation. For most people, that means a relatively small folder. For me, it would likely be a micarta handled case stockman, or possibly a small bench made griptilian (you know, knives I carry a bunch). "Survival situations" include slicing food for lunch or opening packages, removing wayward strings from clothing, and sometimes minor surgery (removing a hang nail). I do have a "beater" fixed blade in the tool box of my pickup, just in case...
Schrade SCHF2SM Extreme Survival Hollow Handle Special Forces 5.6 inch Plain Blade, Nylon Sheath
www.knifecenter.com