I've tried a lot of different backup software, and I keep coming back to this free, open-source tool

Duplicati is a free, open-source backup tool that supports encrypted backups to a wide range of destinations including local drives, NAS, FTP/SFTP, and cloud services like Google Drive, Dropbox, OneDrive, and Amazon S3. It features a web-based UI, incremental and deduplicated backups, automated scheduling, and AES-256 or GPG encryption. A step-by-step setup guide walks through creating a backup job, configuring destinations, setting schedules, and enabling smart backup retention.