Always try to use a lock with a shackle guard. It will make trying to cut the lock with bolt cutters more difficult and they may move on to the next locker.
American A5300 is a good option if it can fit on your locker. I use one on my locker and it works great. It has a decent core, hardened steel shackle, and it is closed shackle to prevent prying attacks.
Would this be similar? I can't find the government versions one Amazon that qualify for Prime.