My thoughts on the cages:
I had a cage similar to the Brisbane cage (different company) and really liked it as it allowed for me to hang longer toys and I felt the cage had enough room for them to jump or climb in. Doors were smaller but was harder for my ladies to jump on me and then run.
One of my gliders started hoarding the food and hissing/chasing when the others would come for food so I bought the..
Critter Nation Double Cage. I love the big doors as it is easier to put the wheels in and it does allow you to close a portion off should you need to separate the gliders. What I don't like is that I can't put longer toys in it, the fact that I don't think it gives my gliders enough exercise (I noticed one has put on weight), and the fact that their droppings are separate (as it my other cage).
What I do to try to correct this issue is: put only the toys on the top portion and not too many so that they can jump around. I put the food and wheels on the lower portion (one on cage door). I also rotate the cages when one cage may start smelling and I let them loose in my bedroom in the morning for their exerise.
FYI..if you get the Critter Cage, you can buy from Amazon coverings made of felt for the ladder and the plastic trays.
How much are you willing to spend? This is my dream cage: www.birdscomfort.com/large-cage-for-small-birds.html