Thermoelectric generators (TEGs) convert temperature gradient into electrical power. The shape (or topology) of thermoelectric (TE) leg has a significant impact which can directly affect TEG performance. The conventional uniform, rectangular TE leg configurations were employed widely in TEGs to evaluate the performance of the TE devices. Different leg geometries have been proposed in the past by researchers to enhance thermoelectric efficiency. However, there is no consensus, nor a systematic study exists to find out the ideal leg geometry and maximize the energy conversion efficiency in thermoelectric systems. The current study investigates various configurations of TE legs such as trapezoidal leg, zig-zag leg, butterfly leg, vertical and horizontal cross-shaped leg, X-leg, Y-leg, I-leg based on their individual shape construction. 3-dimensional finite element simulations are conducted to investigate the thermoelectric output power and conversion efficiency of these configurations and compared to (conventional) rectangular TE leg shape geometries. The reliability and accuracy of the used finite element based numerical model are validated with analytical and numerical results. From the study, results indicate that the vertical cross-shaped and butterfly generate more TE output power compared to all other configurations. The (conventional) rectangular TE leg generates around 1.46 Watts which is around 34% and 25% TE power lower than vertical cross-shaped and butterfly configurations, respectively.