Doesn't zfs kind of solve all the backup problems alone? Technically, no other backup tools can beat it as being the filesystem itself, it knows more than any external tools can know, like instantly know what file got changed over time without scanning the entire tree.

I use Borg as backup of backup (zfs snapshots), so I'll be having multiple implementations of backups (also both are on different remote location) just to be on the safe side.

I don't use any other fancier ones as I don't like risking data on less reliable tools.