Filezilla. Great FTP client. I used it for about a year until it gave me a very serious problem that I still blame for corrupting a remote server.
I have never used an FTP client that allowed you to drag-n-drop directories within the remote server. It is one thing to drag a directory to/from a server, but it is something else entirely to drag a directory WITHIN that server.
If you accidentally grab a directory due to an errant mouse click, it is very easy to blow away a live website. It is pretty easy to do on a machine that may be saturated and slow to respond. A mouse click and drag can confuse a system pretty easily when it is under load.
It happened to me, and it took the better part of a day to figure out what happened and to fix it. After relating this story to a few folks online, I heard from several that it had happened to them as well. It also happened to me a few more times after the serious one and that was when I put down FZ.