Although creatine comes in many different forms, creatine monohydrate is the most popular and thoroughly studied form. It is very efficient, reasonably priced, and backed by research. Other formulations, such as creatine nitrate or creatine hydrochloride (HCL), advertise better absorption or fewer negative effects, although there is inadequate evidence to back up these claims. Consider creatine monohydrate if you want a tried-and-true solution.