They all suck. Like with mail clients. I guess those are two kinds of programs where you have to find the one that sucks less for you
Using Transmit though. But even this sucks because it has some bugs when it comes to upload multiple files at once. This only seems to work on a per-folder base.
However, the ability to mount a ftp connection as a local drive is pretty cool. And it's able to connect to SFTP, Amazon S3 and WebDAV too. But it's Mac only and rather expensive.