The density functional dependence of catalyst activities and linear scaling relationships is important for the rational design of ORR catalysts. The binding strength of intermediates dictates the thermodynamically limiting electron transfer step and indicates whether key binding interactions need to be strengthened or weakened to increase catalyst activity. Thus, for catalysts with intermediate binding strengths, the choice of functional can have an immediate impact on catalyst design choices. We hope that the present work can guide the informed use of functionals for the study of porphyrins and other M-N-C catalysts for the ORR. Hybrid functionals, with the occasional use of DLPNO-CCSD(T) for reference and validation, represent a promising path forward.