I am in the "form follows function" crowd. I would try to answer questions like these:

First, identify what functions are served by carrying any knife.

Second, identify what type of knife or knives best serve those functions.

Third, check your local knife laws to see what restrictions they may place on what knife or knives you can carry, and how you can carry them.

Fourth, within what is legal, identify what type of accesss to knife or knives is necessary to serve the functions previously identified.

Fifth, consider what impression you wish to convey to others, particularly children, by your carry and display decisions.