My plan is to fly from Europe to Australia and back, with unknown airline. So the luggage options should be more or less common. For example, if all airlines accept both carry-on (cabin) + checked (cargo area), or some airlines will only accept checked luggage. Also, luggage allowances (sizes and weights).
For checked seems to be an international standard of 158cm & 23Kg (53x75x30 cm &109 litres trolley).
About cabin sizes, I guess you don't have to carry any special bag, because you take it with you so no risk or somebody opening it. In that case I wonder if you could just carry any cheap $10 backpack or athletic bag and you squeeze it to fit overhead space, so doesn't have to be hardcase costing $200 or such which I've seen.
For checked seems to be an international standard of 158cm & 23Kg (53x75x30 cm &109 litres trolley).
About cabin sizes, I guess you don't have to carry any special bag, because you take it with you so no risk or somebody opening it. In that case I wonder if you could just carry any cheap $10 backpack or athletic bag and you squeeze it to fit overhead space, so doesn't have to be hardcase costing $200 or such which I've seen.