I've been a Cyberduck user for a long time, but since 2.6 was buggy as H*** on large multifile transfers I downloaded the trial of Transmit. I was impressed. Very impressed. Impressed enough to spend $25 when the trial expired. A good, stable ftp client is imperative for much of the work I do, and Transmit seems stable as a rock.
Cyberduck is nice and all, when it works, but Transmit is in a completely different league.
After giving up on the very buggy Cyberduck I paid for Transmit. It's worth every penny. They have a free trial, you probably won't find any better ftp program (apart from the command line ftp ).