Ranked in these QuestionsQuestion Ranking
Pro Easy and intuitive user interface
Pro Free to download
It's free to download from the developers according to the FAQ, however donation models are not allowed on the Mac store, which is why it costs $23.99 there.
Pro Dedicated FTP app that performs well
Sticks to being a simple FTP app without adding more features. No need for other file managing features that are not related to FTP purposes. A client that is simply a nice GUI as apposed to just using a command line.
Pro S3 and WebDav
Browses Amazon Simple Storage Service like your harddisk and supports about any webdav service like box, dropbox, google drive or your own personal nas.