For me it is 'Top. He as a fair Attack and the best Defenses. His only downfall, however, is his terrible movepool. That is why I always evolve Tyrogue into 'Lee first and level it up until it learns High Jump Kick, breed for another Tyrogue (this one with High Jump Kick), and evolve it into 'Top. Also, in the 3rd Gen, 'Top has the Intimidate ability which makes even more of a wall.