If you're looking for a very secure FTP client, WinSCP is the application you need. This software is an FTP client capable of connecting to any server that allows you to do so by means of SFTP implementing SSH. Furthermore, WinSCP integrates totally with Windows, supporting "Drag&Drop" and even shortcut icons (many clients instead of following the link, upload the shortcut,... ). It supports SFTP and SCP by means of SSH-1 and SSH-2, as well as FTP protocol, less secure but with greater compatibility.
FTP client that makes use of SSH
It's also possible to use the command-line interface to launch batch file scripts, so many tasks can be optimized by means of WinSCP. Moreover, it includes a text editor and it supports passwords encrypted by means of SSH, public passwords and Kerberos.
Its interface is a classic on FTP clients, with the window divided into two parts, one that shows the remote server and the other one that shows our computer. How it works is really quick, it loads the folders very quickly and working with WinSCP is really easy.