My automated workflow is to package up backup sources into tars (uncompressed), and encrypt with gpg, then ship the tar.gpg off to backblaze b2 and S3 with rclone. I don’t trust cloud providers so I use two just in case. I’ve not really been in the need for full system backups going off site, rather just the things I’d be severely hurting for if my home exploded.

But to your main questions, I like gpg because you have good options for encrypting things safely within bash/ash/sh scripting, and the encryption itself is considered strong.

And, I really like rclone because it covers the main cloud providers and wrangles everything down to an rsync-like experience which also pretty tidy for shell scripting.