We use both
HEYS brand with AWD I just use zip ties for the lock they never seem to bother
I used locks & they cut them off
At the port I use locks only once in Miami did someone try to cut it off & they must have been interrupted as they did not cut all the way through
If someone wants in the bag they will do their best to get in
Once had a bag with the separate zip on the side someone slashed through on the inside into the main bag
Some days you just cannot win 🙄