Personal: cloud server (it's quite expensive, like 40€/month but it's the best I could find) with rsync without --delete Pro: backuppc (used at a "large" scale

Personal: cloud server (it's quite expensive, like 40€/month but it's the best I could find) with rsync without --delete Pro: backuppc (used at a "large" scale without issues) or snapshots on big fileservers