I'm thinking about the amph bot factory. It is good on any terrain: On water, it has submarines; on land, it is competent; on mountains, lobsters and djinns.
Furthermore, most of the top players are good because of better economy, not because they micro their units: The best players have a significantly higher amount of reclaim & metal prospector awards, and they have a significantly negligible amount of decorated veteran awards. And amph bots discourage micro, since their units are not maneuverable. Because amph bots are not very maneuverable, they should be perfect for teaching the economy part of the game.
Does this mean that amph bots are the perfect factory for learning the game?