Frequency synchronization of power generators is a necessary condition for the operation of power-grid networks. The robustness of synchronous states to disturbances can be quantified in terms of their stability Here, applying a combination of perturbative analysis and numerical optimization techniques, we explore the landscape of synchronization stability in the space of generator parameters. We find that there are assignments of the parameter values that maximize stability beyond what has been found for identical parameters—the best previously known assignment. We suggest that this discovery may lead to a systematic approach for identifying parameter choices that can enhance synchronization of any given power grid.