I’m pretty sure FTP is never encrypted. Not sure about overall security from access. SFTP is the best as it has modern security and encryption so no VPN needed.

The only reason I have FTP at home in an old printer that only supports it for wireless scan uploads. Rsync with SSH is the best, learn what -a, --delete and --checksum arguments do - they are very powerful. To strictly answer the question - SFTP.

rsync over ssh is my preference, otherwise sftp. Don’t use ftp, everything over it is plaintext including your login credentials.

SFTP is more secure than FTP

Do not ever use unencrypted protocols. Why should you?

There’s no much overhead nowadays with current hardware.

scp

Should I use FTP or SFTP when downloading files to a PC from a Seedbox?

What is safest when not using a VPN?

Do not use unencrypted connections. There is no reason to ever use an unencrypted connection. FTP is obsolete, it was used in a time when encrypting and decrypting data was too resource intensive for the processors available.
That time has long since passed. People have been born, have grown into adults and have had children of their own since then.
Don’t use ftp, don’t use http.

Use SFTP or FTPS, plain FTP should not be used.