I have struggled with a one size fits all approach to this small office scenario.
I have used file sync programs including SyncToy, and they work, but users forget to store the data in the synced folders, so a no win.
I have used windows backup (it comes with MS product for free), but requires that people actually perform the backup, and have the skills to restore.
I have used copy programs including xcopy and robocopy and other derivatives. These all work well, but again it comes down to storing data in the right locations to ensure that the copies are performed. Also must either manually run or script.
All the above methods rely on there being an existing operating system, and the required application being operational, before the backed up data is restored and accessed. And this takes time when there is a catastrophic failure.
I have used disk clone software such as GParted to clone partitions onto removable Hard disks. This gives the advantage of just inserting the drive into another machine, sorting the errors, and you are operational. But it requires the skill to manage partitions and to sort the various driver incompatability issues.
So what I do now is to use an imaging tool, currently StorageCraft ShadowProtect. I take full backups of the machines, often multiple partitions, and take them offsite on rotating USB drives. Hardware Independent restore of images, to just about any hardware is possible. If I want to do a quick look into the files, the storagecraft ISO allows boot from CD and has file browser tool. I regularly restore to Virtual Machines to resolve issues.
Only real trap is the windows activation when taking OEM from original machine to VM, but there are ways around every issue.
So many ways to backup, and none perfect. But I have standardised on StorageCraft for now, and am happy to pay the license fee, just for access to their support people, on the rare occassion that I encounter issues.
Additionally, I do not work on a customers machine, unless I have an image. I call it insurance.