It all comes down to the type of training you are looking to do. There are many great certifications out there and each one offers a little different option than other ones. I like to work mostly with athletes and people who have depend on being in the best possible physical condition so they can perform their job (law enforcement, military personnel, firefighters, etc.), so I chose the CSCS certification. But each trainer has different goals and target clientele which he/she wishes to work with and so they have to decide which certification(s) will be the best choice for them. A certification by itself is not enough to make someone a great trainer. They need a combination of education, experience and a great attitude as well.