Jack actually may know the answer to this specific conundrum.
I would think that development would vary from club to club, coach to coach rather than league to league. It's just that some kids seem to appear on the Tac cup radar easier in some leagues than others. Do some research and see which clubs produce the most kids for tac cup sides.
Having said that though,we had kids choosing to play seniors at my club in a bush league under a former ovens and murray senior player rather than to head into under 18's ovens and murray (as is normal practice for talented juniors as they come under the notice of the murray bushrangers) as they felt their development would improve under the coach, rather than the league.