Most performant transfer protocol for external data directory

Hi everyone,

I rented a small Vserver and a bit of FTP storage. My idea is to mount the FTP storage in my vserver and put the data directory inside to save storage capacity on the machine. My FTP server provides SFTP, SCP, Samba/CIFS, or WebDAV protocols. Which one would you choose for the best performance?

Thanks in advance
hagen