OpenVPN or FTP for updating web server

Which is a better method for updating our website, which is located on our DMZ? I could either set up an ftp server on the web server or set up OpenVPN to directly connect and send the files that way…is there one method that is better than the other?

Also, if using OpenVPN, how crucial is it to add something like OpenSSL to it for remote sharepoint access or even the above situation such as remotely updating web site files?

Thanks,
Paul