I have something similar to @patdavid’s setup. The work computers are rsync’ed to an external 3TB USB drive. There’s a second USB drive at my parents’ house, and every time I visit I just swap. Both drives are luks-encrypted in case of robberies. The drives are btrfs-formatted, and on every successful rsync, my script makes a snapshot (having snapshots has saved me many times, and I wouldn’t call it backups without some way of going at least a little bit back in time). Since the drives are encrypted, I just backup everything from the home directories (with rsync excludes for ~/.cache and similar).
The only issue is that those 3TB are filling up, and 2x4TB is a bit expensive (and I don’t want to start raiding drives together, which will make things take more physical space and mean more things that can go wrong etc.). I’ve seen “unlimited” cloud storage providers, but 1) the first upload will take forever and 2) none of the unlimited ones provide client-side encryption and 3) they typically require some proprietary client-side program that needs to survive updates and linux support etc (there’s always something). If tarsnap comes with an unlimited option maybe, but I find that unlikely.