In this work, we perform high-throughput computational screening to compare trends in C-H hydroxylation reactivity of an initial catalyst set containing over 1500 mononuclear, homogeneous Fe and Ru catalysts at a single +2 oxidation state and three spin states. We curate a subset of over 200 catalysts that are identical except for their metal center (i.e., Fe vs Ru) to isolate metal dependence. We demonstrate that differences in C-H activation energetics between Fe and Ru catalysts are sensitive to the spin state. We also show that widely employed LFERs in C-H activation do not generalize for both Fe and Ru or across spin states, yet Fe catalysts present a greater opportunity to disrupt LFERs compared to Ru catalysts when evaluated over all spin states. We propose C-H hydroxylation spin-reactivity trends for both metals as deduced from spin splitting energies. Finally, we compute full free energy landscapes for representative Fe and Ru catalysts to compare their kinetics and catalytic turnover frequencies and examine the validity of BEPs in C-H activation catalysis for polyolefin functionalization.