Luggage locks are basically only a deterrence against casual crime-of-opportunity thieves or pickpockets. I've found it's much simpler to just use a zip tie on my zipper. Very easy to put on, easy to take off again once you get to your destination (nail clippers work well), and provides roughly the same security as a TSA lock. And it has the added benefit that you can tell if the TSA opened your suitcase because the zip tie will have been removed (whereas with the lock the TSA can look through your suitcase without leaving any indication).