I cannot say anything for the ferret nation, having not had one with that lock system, however this one does have a secure lock. The way the lock works is by sliding over and up to open and sliding down and over to lock. As long as the lock is slid back into place it will not open, however if you don't slide it over, I have had my ferrets knock it back open when I didn't lock it all the way.
From what I see of the ferret nation, it seems to be a type of lock you squeeze one set down and one set up to open? I would say that the prevue is easier to use, however the nation is probably either equally or more secure, but I can't say for sure without knowing how easily the nation gets stuck or if it always slots back into place right, which would be my worries.