If a lock is sticking, it may not be the fault of the lock. It may be the maintenance!
I do volunteer work for the SW PA Red Cross and we have trailers all over the region where we keep stashes of emergency supplies. We were having trouble with the pad locks siticking or even freezing up completely. We assumed that they were rusting up inside. So, I contacted two major lock manufacturers to find locks that wouldn't rust: I discovered that the locks we were using were all brass inside and could not corrode. Instead, we had been "lubricating" them with WD40 a couple times a year. BOTH lock manufacturers told me that that was probably the problem.
They told me that WD40 works for a short period of time and then the solvent in it evaporates and leaves a sticky residue behind which gums up the inside of the locks.
Both lock companies recommended "lubricating" locks with graphite only. One of them even sent a tube of dry graphite that you spurt into the lock. We have been using that technique ever since and have not had any more problems with sticky or frozen locks.
... Of course, if you buy a cheap lock that will rust inside, nothing will help....