The effect of symmetry in design can vary based on the context and purpose of the design. However, if we were to broadly assess the impact of the options provided, vertical symmetry typically has a more significant effect on design. This is because vertical symmetry is often associated with balance, stability, and formal aesthetics, which can create a strong visual impact in various applications, from architecture to graphic design.
That said, the choice can ultimately depend on the specific design goals and the message the designer wishes to convey. Each type of symmetry has its unique characteristics and applications that can significantly impact the overall design.