I would recommend Brass.
Care should be taken to avoid the knockers that are too harsh and have a disturbing noise.
When someone knocks at the door, do the children get excited and welcoming or do they fear and run away from the door?
That will tell you if the door knock is suitable.
For shape, the consideration could be whether the area is secure and only the welcomed guests would be visiting.
In some parts of the country, they use a figure to scare off the evil eye the unwanted intruders.
so if you are sure that primarily the respected and expected guests would be knocking the door, the door handle need not be Lion shaped but may be pleasing figure, say elephant shape.
Good to have pleasing photo of Shri Ganesh on top of the main door.
Let me know your views.