A systematic Monte Carlo simulation has been performed on the adsorption of CH4 in a series of 10 metal-organic frameworks (MOFs) to confirm the desired characteristics of an optimal adsorbent for methane storage. The simulation shows that high isosteric heat of adsorption, specific accessible area, free volume, and low density of framework are all desirable properties for a material with high adsorption capacity. However, not all these properties are compatible, and there exists a complex interplay of these that influence the uptake of methane. We conclude that the accessible surface area and free volume play a main role in determining methane uptake at 298 K and 3.5 MPa from this simulation.