Give this one a look, FTP Voyager.
Having used most of the ones mentioned in this thread over the last dozen years, this one has proven to be one of the best ones I've ever used and is ridiculously reliable. It's also one of the most solid performers I have used yet for sFTP (FTP via secure shell / ssh2), with steady transfer rates up and own.
http://www.ftpvoyager.com/
One of the worst performers I have used has been CuteFTP, although it's been several years since I have used and perhaps that one has improved. I did give Filezilla a try recently, more out curiosity, and thought the interface was very poorly done. That of course if just my opinion, but I am quite happy with FTP Voyager over any others I have tried.
One nice thing here is that the interface is very customizable to however you prefer it.