I agree with the knife you always carry will be the one you will use.

One thing to remember is if you are going into a know area that you need a big knife then I would carry one. Basically carry the right tool for the element you go in, I always keep a big chopper in my BOB but not on me.

If you travel in some countries or by ship, train, bus or plane, you will probably not be allowed to carry any knife or in some cases they may have you put it in checked luggage. And when something goes a muk (plane crash,train wreck, ship sink or what have you) it is highly possible you won't have any knife on you and the point would be mute. So, depending on the terrain and country would determine what I carry. I don't need a chopper in the desert but if I go in the jungle I will have one. When traveling I usually have to buy what I need on site than to fool with customs. I haven't been to any country yet where I can't get a knife or lighter on site.