My every day carry knives are a Benchmade Griptilian and a SAK Executive. I use these as most of us do to open boxes, cut string, tape, tubing, plastic seals, etc. I work in a laboratory environment. Of I'm outdoors I carry a neck knife, usually one of my own or an A.G. Russell Woodswalker as well as a sheath knife ranging from an old 1930's KA-BAR hollow aluminum handled hunting knife with my own mini kit in the handle. (This knife was made before the way "Rambo" knife craze spawned every cheap knife in the world with a hollow handle.) or possibly something more substantial or lighter depending on where I am and how long I will be out. If I'm camping I invariably have one of my Philippine Bolos as well. I use this for chopping fire wood and other heavy duty jobs. My maxi kit always contains one of these to be used not only for chopping wood but for building shelters, making traps and other improvised equipment out of wood, cutting vines, splitting small logs, butchering game etc.
I have been a knife colector for many years and I choose my carry knives much the same as most men choose their clothes for the day, taking into account necessity, portability, style, and just a feel for a certain knife on any given day.
Kix