Johnathan great question.
In order to answer the question I would say it depends on what type of welding are you looking to get into. Are you looking to do tig, mig, underwater, or other types of welding? Depending on the type of welding you are looking to get into would be the type of certification you would need. It would also go along with what type of work you were looking to get into for example, are you looking to work on the shipyards or in a architecture type of environment? This would determine all of the certifications that you would need.
Hope that helps.