Hardware apart there is a freebie called EZBackitup which can be configured to update only files that have changed, or even delete files no longer present in the source folders.
It opens in a Windows Explorer type of screen, will take time to decide what is to be copied and where to put it. Also a minute or two to make the first backup.
Thereafter it runs like smoke to deal with docs and databases. Barely time to click the green tick and job done.
Try click here - there are lots of alternative sites if you use Google.