If you may ever move, this matters more than almost anything else on this page, and hardly anybody explains it before someone has already paid for a course.
Two national bodies accredit certifying agencies: the National Board on Fire Service Professional Qualifications, universally called the Pro Board, and the International Fire Service Accreditation Congress, IFSAC. They do not certify you; they accredit the agency that certifies you, against the NFPA standard.
A certificate carrying a Pro Board or IFSAC seal is far more likely to be recognized by another state. Reciprocity is still granted state by state, on that state's terms, and is never automatic — but an unaccredited certificate makes an already awkward conversation much harder.