Borgbackup is great. It uses block-level dedupe so you can store months of daily backups without using a lot of space, and don't have to do full backups every so often like with Duplicity.
It has an "append-only" mode that prevents the client system from being able to delete the backups. This means that even if the client gets hacked, the attacker can't delete the offsite backups. This is a common problem with other backup solutions - the client system has full write access to the backup, so an attacker (or ransomware) can wipe all your remote backups before locking/destroying the local files.