Back when I started doing web design, there was only one *real* ftp program that I knew of - WsFTP. The standard upon which all of the two-paned FTP GUIs are based, WsFTP was also a very simple program - just click the '->' button to move a file from one server to another, and '<-' did the opposite.
That worked well for me, until I started to use Linux. Once I learned the beauty of the command line, I began to avoid the mouse as much as possible. Furthermore, I needed a new FTP program, since WsFTP only ran on Windows. For a time, I settled on the original command-line 'ftp' program, but that quickly became annoying - it was just too simple. I tried some wxWindows clone of WsFTP, but that just seemed an uncomfortable hack.
Fortunately, at some point, I discovered NcFTP (why do ftp programs all need absurd capitalization? just curious...). It opens in a console, and does its job simply and effectively. Here's what I'll do when I'm done writing this blog entry to upload it to my server:
> open blog > lcd ~/code/web/mysite/blog > put underappreciated.txt
And that's it. 'blog' is a bookmark which connects me to my remote server and changes to the proper directory on that server. To set it, when I'm in that directory already, all I have to do is type 'bookmark blog', and it will ask me if I would like it to save my password with that bookmark. This is opposed to the aforementioned GUI programs, where bookmarks existed, but were rather complicated to set up.
Furthermore, the 'lcd' and 'lls' commands allow simple local navigation, and the program has directory and file name completion on the remote server as well as the local machine.
In short, NcFTP is an example of a program which is complex enough to get the job done efficiently, yet simple enough to use with no learning curve. As you get used to it, you simply learn more commands, which I find to be a hallmark of a good program. If you don't use it, you should check it out; you probably already have it if you're on a *nix, and it works with Cygwin if you're on Windows.