Start with the basics, everyone should have a quality knife on hand for emergencies. I thought the following quote by James Mattis was absolutely brilliant so I had to add it to my post.
"My good reason to carry a knife is that God gave me rather weak teeth and rudimentary claws in an evolutionary trade-off. The hairy-armed person who figured out how to put an edge on a suitable rock made it possible for us to be recognizably human in the first place. I wear a wristwatch whether or not I have an appointment to keep, and I carry a pen and/or pencil because I am a literate person whether or not I have a specific writing task ahead of me, and I carry a knife because I am a human and not an ape.
A knife comes in handy for all sorts of random tasks that involve separating matter. Like cutting a string, or making a sandwich, or opening a package. It can also come in handy in an emergency, which need not involve a human assailant, and emergencies are by their nature unforeseen, so one should carry a knife all the time."
I readily concur with Mr. Mattis. To be prepared you must have an adequate blade. My personal choice as a daily carry is the SOG Trident TF-6. I like the Tanto blade for a working blade because it's a little more stout at the tip. For my Bug-Out Bag (future post) I keep a SOG FP-3 Field Pup hunting knife with a SOG B63 Powerlock E.O.D (Explosive Ordinance Disposal) Multi-tool in the pocket of the Field Pup sheath.
In my opinion the average survivalist should doesn't need a huge military knife for time in the bush. Your going to be skinning & dressing game, building improvised traps, tools and shelters. For these tasks your better off with an approximate 4" blade which is why I choose the Field Pup.
I hope this helps.