I use a zip ties on my luggage. If you are locking your luggage, just at the port, you can use any type of lock you wish.
The truth on luggage theft is this: Your luggage is with you for the entire time until you check it in until you pull it off the baggage carousel. If a baggage handler wants to get in your luggage they will. They can pop off a lock or a zip tie in no time. They can also pop off a zipper tab or slash open the teeth of a luggage zipper with a screw driver or small knife in less time then you can unlock the lock. Luggage locks keep honest people honest, the zippers closed and gives the owner a sense of security.
They can also pop open most hard sided luggage in almost the same amount of time.
The best thing you can do is keep ANYTHING of real value with you, in your carry on, and don't let it out of your sight. You may want to put a lock on the carry on to delay someone from doing a quick grab from one of the outer pockets.