An option to create wrap-around maps (by allowing movement from a tile on the edge of the map to the corresponding tile on the opposite map-edge)
The corners of a map are usually a huge advantage for any player that can grab them. A torus has less corners than a rectangle. Therefore, I would prefer playing on a torus.
It should be technically pretty easy to connect the tiles on opposite edges (EAST-WEST and NORTH-SOUTH), AFAIK, even pathfinding should remain the same.