This comparison study investigates the influence of subchannel symbol rates on the Wavelength Selective Switching (WSS) filtering penalties in elastic optical networks. Within these networks, WSS is essential for the signal filtering process. This study compares and evaluates the filtering penalty for several modulation styles and subchannel symbol rates, including variable and fixed subchannel symbol rates. This paper investigates the performance of WSS filtering and its sensitivity to these parameters through comprehensive testing and analysis. The findings enable the improvement of WSS filtering efficiency in elastic optical networks by illuminating the ideal subchannel symbol rates. This study advances effective signal processing methodologies in contemporary communication systems.