What changes the cages answer
Choose a rectangular cage with clear corners, safe bar spacing, and enough width for the bird to move. Round cages often look decorative but do not function as well for daily care.
Corners help birds feel settled
Many birds use corners and cage sides as reference points. A round cage can make the space feel exposed and harder to arrange.
Perches and bowls are harder to place
Good cage layout needs perches at useful heights, bowls away from droppings, and open movement paths. Curved walls make that less practical.
Decoration is not the job
Bird cages should be chosen for safety, space, cleaning, and behavior support before style.
Better default
Use a roomy rectangular cage unless an avian professional has a specific reason for another setup.