Avan
I think plant creatures. for the army and the reason is this: the plant creatures can be raised before the battle, you can use as much time as you need to train and strengthen them, they have independent thought and, depending in the seeds you use, can have different innate talents allowing for more diverse strategies. their main drawback is more resources invested and less available at a moment's notice, but they cost zero energy when you might need it and have been shown that some at least have a higher potential combat power