Being a knifemaker I usually have a few knives handy, for my PSK I have a Ken Onion leek. Never been used, but will be sharp when I need it....

There are several knives that I use regularly, the main one being my bushman's mate. I have one that I have used for years and it has never failed me.

That being said there is only one knife that I keep in my BOB and that is the first knife I ever made, it is a drop point hunter with a 3/16" thick 1095 damascus blade (4" blade) and a solid tang. It is one knife that takes a licking and will still shave. I can rely on it to not chip, not break a tip when being abused, and it can be used to split firewood when needed.

I have had a gerber survival knife and other bigger knives, but I have found that they just don't work for general use and are too big to be safe in some situations. I would never have a knife blade longer than 6" for general use around camp, if I had the choice, and 4" works fine for all I need. In a jungle take a machete too!