FTP clients are basically offering almost the same features nowadays, guess it is hard to think of anything new to add to it anymore.
I used to have CuteFTP, later changed to smartFTP then FileZilla and now FireFTP !
I love FireFTP because it runs in FireFox (it just open a new tab in your current firefox browser window), I don't need to minimize the browser and launch FTP program, upload then bring back browser window to check, and switch again to FTP for upload etc.