We're setting up a web server at our workspace. In conjunction, we're planning to install an FTP server, however I'm stuck at what protocol to employ -- FTP, SFTP or FTPS. I googled around, trying to see what protocol offers what, coming across articles like this, but I can't make up my mind. Only simple, once-in-a-while file transfer is desired; however, security is a concern since the file server is intended to be accessible from the internet.
What protocol is the most apt for my use, and why?