I wrote my recommendations for online backup solutions a few years ago (back in 2010) but today (2020) I personally prefer using Google Drive. They have an app you can download and install on your PC and it will automatically sync your files and folders in realtime. Even works with Access databases (as long as the file isn't in use, which it shouldn't be overnight unless Karen in Accounting forgets to log off AGAIN).

I'm going to be posting a video soon on how to set up Google Drive Sync and how it pertains to Access. Stay tuned.