There are not a lot of options that I’m aware of, unless things have changed in the last year. We ended up just using a third party (non .NET) app that was scriptable: http://winscp.net/eng/index.php
We created a script, and called it from within our .NET app using the System.Diagnostic.Process class.
However, Rebex DOES have a .Net component for this if you’re willing to pay for it. There’s also a good explanation of the difference between FTP, FTPS, and SFTP.
solved How to connect to FTP Server using SSH FTP or SFTP in C#? [duplicate]