I have a vast collection of many different types of knives from different makers.
I have everything from flea market cheap knives up to very expensive ones made by SOG, Cold Steel, Kershaw, Buck, and so on.
Oddly enough, I tend to carry a SCUBA dive knife. Mine has a 6 inch blade, is semi-serrated, and has a non-conductive, non-reactive plastic grip.
Just because this is my ideal knife . . . it doesn't follow that you should imitate my example.
I carry a dive knife because I live in Florida, where it's humid, salt air, and lots of estuaries. I throw my dive knife into the pack when I go kayaking, hiking, or camping.
My knife doesn't rust in the way that another field knife might. After SHTF, I expect to get lots of food from the water. We have taro (a starchy semi-aquatic plant used to make poi), edible seaweeds, cattail, shellfish, and so on. A dive knife seems appropriate for my situation when it comes to harvesting these foods.
Also--because it's a dive knife--it holds up better when dealing with chemicals, gasoline, motor oil, corrosive acids, transmission fluid, and so forth. Exposure to these substances hasn't hurt my dive knife, but I suspect that a regular field knife might get damaged or destroyed . . . especially if it has a wood or leather grip.
Lastly, the plastic grip is good insulation from electricity if I'm using it an urban environment and am concerned about power lines.
This is my exact knife, but the image is from the Internet, as I have problems using my phone camera.
The blade is 6 inches long, and this knife is compatable with several different kinds of ballistic nylon and/or leather sheaths designed for other knives.
I got mine new about 25 years ago when I became certified in SCUBA, and it's still going strong . . . although I've had to replace the leg straps. It's a subjective thing, but I like the balance and "feel" of the knife. I keep it clean, and occasionally use silicone spray on the blade.
Not bad for a blade that sells for $20.00 to $30.00 on ebay.
That's my take on an ideal knife, but that doesn't mean that you should follow my example. My environment and lifestyle is probably quite different than yours.
Also, try to communicate with Roninsensei. I consider myself fairly knowledgible about knives, but he's a specialist who can be considered an actual scholar on knifes, metalurgy, retention systems, and so on. I know enough about metalurgy (my grandfather was an engineer and a physicist in a nuclear power plant for Kerr-MaGee, and my great-grandfather was a college professor in mechanical engineering . . . and both of these men were avid hunters, fisherman, and outdoors people. They--along with my mother, who always carried multiple blades--introduced me to the virtues and pitfalls of different knives) and edged weapons to be able to spot a bullshit artist when it comes to blades . . . and Roninsensei does not trip any of my bullshit alarms. So, I tend to believe that he's the real thing. He is on this forum, so try to see if you can explore your questions, concerns, and ideas with him. Just be curteous and reasonably polite . . . and don't try to bullshit him.
Also, look into a Swedish author named Martina Sprague. She is a martial artist who happens to be an expert on bladecraft, so check out her books on knife fighting.
I sent her feedback via email, and she was very curteous and responded to my points in an intelligent and informed manner
She is refreshing, as she gives an interesting European take on prepping. Her point of view is quite different from the average American prepper, but her ideas seem very valid and worthy of our study and consideration.