What type of traveling, by car, nearly any bag will do. By bike, foot, may need to carry more at once as you dont have a car to carry the load and only choose what you need at the moment. Plane, well you might want to find out what TSA will let you through with but other then that you dont want a bag too big it will be checked, you also dont want too much crap your getting a full cavity search every time you go to the airport.