I've only used free or open source system image backup apps such as
EaseUS Todo Backup Free. Have successfully restored many hard drives using it. In fact, all with no issues. However, some valuable features on the free version have been eliminated. Such as encrypting image files, and only offering an incremental backup option.
Personally, I prefer differential backups as incremental generally involves many more smaller files, which can break a restore if any one file becomes corrupted. So less reliable IMO.
I now use the free
AOMEI Backupper with features similar to paid backup apps. Such as offering differential backups, and can encrypt images with a password. Clean interface, and can easily schedule backups, or mount the image to access files.
For local backups of key folders or files continuously, I've been using the free version of
PureSync. Handy for automatically backing up files such as Firefox or Thunderbird profile folders on more or less a continuous basis. But cloud apps such as Dropbox can do the same thing.
However, features in their free version have also been reduced. Used to be able to setup backups/syncs of important folders or files as as soon as a change in file was detected, or when closing the application. Now only available in paid version, as syncing locked files. Have now set folder backups based on system idle time, or when logging off. But can easily select any folder for backup by simply right-mouse clicking and setting options.
Also use the free, open source
FreeFileSync, which can backup locked files. But the interface is not as clean, or straight forward as other file backup/sync utilities.