Actually, the original poster asked for ssh file transfer apps, not front end ssh. Anyways, I would be wary of fugu if it is merely a front end to the existing command line tools because the baseline ssh tools installed in OS X are not very good -- in particular not supporting resuming of upload/download. So unless fugu has reworked the ssh intrinsics itself, it is always going to be at the mercy of the features (and lack thereof) in the installed OS X ssh commands.
I perform a lot of 1GB file transfers requiring 1.5-8 hours depending on available bandwidth, so the resume feature is an absolute must for me.
And again, I would warn anyone using a front end tool to verify that the file transfer rate is not slowing down. This is the reason that I dropped CyberDuck. It resulted in file transfers 50% slower than what lftp did for the same sftp:// protocol transfer.