Asking knife people to pick out their most prized blade is like asking a parent to pick out their favorite child.
Some will be able to, but most won't say just one, even if there is one that is truly 'the one'.
Got this first one in Afghanistan about nine years ago. It's important - irreplaceable - as a memento, but it just sits in the safe and does nothing. I've never even cut anything with the old thing:
Three favorite pocket knives are next. The red one is a Vic Tinker. I bought it after I got out of basic, and carried it all over the world. I've used it on more continents than even I can believe. The scales are loose now, and the tip of the smaller screwdriver is a bit buggered from some stuff I had to do with it one time, but the blades are sharp and ready to go, and it rides around in my backpack most of the time. I got a Vic Soldier (the nice looking Alox one, not one of the funky new ones) that I carry more now, and semi-retired the Tinker, even though if I glued the scales down, it'd go for a lot longer before it was actually worn out.
The old scout knife I carried as a scout leader.
The blue Case I bought while I was on leave from the desert, so I could carry something pretty back there that was just designed to look nice and cut stuff.
This is a knife I got from my dad, and then carried all over the place. It's got a five inch blade - just long enough to be serious, but not so long as to be obnoxious and in the way. A good length for a knife you can actually use, but sharp and pointy, too.