I find it difficult to set up a good system for encrypted storage.

1. Cryptomator: it's immature and buggy, especially the 1.5 version. See comments in forum.cryptomator. The files and folders disappear, vaults crash, vaults fail to mount, etc.

Boxcryptor is the paid version and not buggy. But it's not open source.

2. EncFS. Has security issues that haven't been resolved.

3. CryFS. Too slow and immature.

4. Encrypted backup, like rclone or duplicity. These are not sync tools.

5. eCryptfs: Used for Ubuntu home encryption (even then somewhat outdated), not for cloud.

6. AWS KMS: server side encryption; amazon has the keys.

7. Gocryptfs: It's OK. Reasonably fast. Cons: command line only, and for Linux. Uses OpenSSL library which isn't all that secure.

It seems to me gocrytfs is the best among these.