It depends on your equipment.
Your going to have to try it in your own system, to see which one would be the best value for you and Your System.
I have tried all three on the last tour.
The Areo Ag is definitely the star of the group.
The Areo Cu is a step above the Ember.
I ended up keeping my Ember, the price difference was too much for my budget at this time in my audio journey.
But before I upgrade any other components, I will consider purchasing the Areo Au First. (Whoops Ag)
I also wrote a short review of my time on the Areo Tour.