Never pay a ransom: it just encourages the bad guys to try harder. Soon they will figure out how to corrupt your backups as well (if there is anyway to do that - now we are in an arms race). Better to write off the loss now and ensure the bad guys don't continue to think of new attacks.

There is one exception: if the ransom is paid in such a way that the FBI (or equivalent) can track where the money goes and thus arrest the criminals.