Carbon Copy Cloner. I have used its backups to restore entire disk images with perfect results - both when upgrading hard drives and when downgrading an OS update. The new 5th generation is the easiest clone App in the world to use and it is ready for both HFS+ and APFS. Automating backup tasks is a very simple process. I like Time Machine because it protects against certain types of corruption and file modification that a clone does not - but, if I have a usable clone, I strongly prefer using this over Time Machine when doing a restore.
I am guessing you are doing this already, but, if not, consider using two separate drives for your bootable clone and your Time Machine (and if you want protection against power-induced data loss, the clone should be physically disconnected from the computer and power outlet when not in use.) If you do use the same drive (which I would not advise), be sure you have partitioned it correctly so that the image and Time Machine files are on different volumes.