If you use Firefox and your FTP client needs are simple, we like the FireFTP add-an for Firefox:
https://addons.mozilla.org/en-US/firefox/addon/fireftp/
You may also want the button to more easily start FireFTP:
https://addons.mozilla.org/en-US/firefox/addon/fireftp-button/
FileZilla is a great FTP client…easy and free: