Should a contact be solder or crimp

One question I have been ask a lot is should you solder or crimp a contact. When you crimp a contact you get a perfect crimp every time and the failure is very low. The problem with soldering is most people do not know how to do it right and they get a cold solder joint. Also when soldering excess solder remains on the contact when could cause a short when falling off or touching another contact.