[JZL003]

I've never done that many but rclone is famous (imo reliable) and very cross platform. It also supports an encryption layer it controls over top of generic cloud providers

So I've been enjoying b2 (as an example, you can Fuse mount to browse the files without downloading). But just for backup don't Amazon glacier or Google cloud archive is so so cheap. If you wanted to be paranoid you could do both separately

I haven't independently audited rclone's encryption layer