I sync my home directory between my two primary machines (iMac and laptop) using
Unison. This lets me walk to a different machine and work on things if my laptop falls into lava.
I backup all my machines via Time Machine to a Synology NAS. Time Machine lets me keep a backup history and retrieve files in a one-off fashion if I need to. I can also do a system restore from Time Machine if I need to.
I also backup my home directory and certain other important locations to the cloud using
Arq Backup. This includes certain directories that are stored on my NAS (photos, archived documents, etc). This helps protect against NAS failure and fire/theft/etc. (For example, when my old Drobo stopped recognizing its drives and Drobo Support was useless, I could give up on it and restore important things from the cloud.)
I use CCC to backup my server Mac nightly so I can reboot into the clone immediately. I don't usually use CCC on my laptop or iMac, because I keep the files across multiple machines, and because my MBP is almost never at a desk or somewhere that I would plug in an external drive. I do use CCC when I'm doing OS upgrades or taking a machine in for service.
Combined, this gives me good confidence that I can recover from various forms of failures.