Buy anything... don't expect them to last. These can get easily damaged. Wheels will fly away. The airline will of course reimburse you if it's damaged beyond repair. Many airlines have a max 30 kg limit. This is because of health & safety of baggage handlers.
So any bag that can handle 25 kg is fine. Check with the airline as most of them have a higher weight limit for migrating passengers.
If you are flying Cathay, you can take a seperate laptop bag with you. Just make sure its reasonable small (around 40cmx30cm). This is not counted for the carry on weight limit.