In this work, the spatially dispersive behavior of three different metasurface geometries has been investigated. A patch-like, a strip-like, and a fishnet-like unit cell have been compared in terms of their surface impedance for different angle of incidence at terahertz frequencies. The fishnet-like metasurface shows a TE-TM polarization independent behavior and a remarkable non-dispersive behavior, opening to very interesting possibilities in the design of Fabry-Perot cavity leaky-wave antennas with a reconfigurable pointing angle and equalized patterns at terahertz frequencies.