JASS  I've use Transmit for 6 months. I only use the SFTP protocol. For just $25 it's much easier to use than

an sftp from the terminal or ssh tunneling + a server connection. It has all the features I need and use. You can pre-set file permissions on uploads, you can set it to ask you what to do if a file of the same name already exists, you can have multiple connections open, and it supports a tab-bar like Firefox/Safari for your connections. Perfect little tool!  
(Version 3.5.6)

JASS  Installs easily. Good informative installation menu and good informative preferences menues. Ran it for 30 minutes, but really disliked it and thus wanted to uninstall it again. Guess what: there's no uninstaller! You manually have to remove it in /Applications/, remove the prefs.list for every single user, and clean up your System Preferences. A program without a clean uninstaller! No thanks. I'd rather just delete directly from ~/.Trash using a script.  
(Version 1.8.8)