Macaws - require a cage far in excess of most cages available here in Australia. Have an aviary builder custom-make you a suitable cage. The results will be well worth it and may well cost less than an imported, commercially-constructed cage. Conures and Quakers - love to sleep in a nest box or small log at night, so buy a cage large enough to accommodate this if you choose one of these species. The design of the cage is as equally important as its size.
Hexagonal cages are also fine and offer a variety of perching options.
Cylindrical cages should be strictly avoided, as these are often restrictive size-wise and can cause birds to feel insecure, leading to behavioural and psychological problems. An enclosed section is beneficial in offering your parrot a sheltered area, especially if the cage is to be kept outdoors in areas exposed to climatic changes. Most available cages lack such an area, so you may have to add a small roof section or enclosed area yourself. A removable base tray will make cleaning so much easier. Avoid cages with plastic trays, as these are easily broken and not replaceable.