Ranked in these QuestionsQuestion Ranking
Pro Free and open source
FileZilla is free open-source software distributed under the terms of the GNU General Public License free of charge. Basically this means that everyone, including corporate entities, can use FileZilla, including but not limited to private, educational and commercial use.
Pro SFTP support
Supports FTP, FTPS (SSL) and SFTP (SSH)
In addition to Windows, FileZilla client is available for Unix, OSX and Linux.
Pro Suppots FTP and FTPS
FileZilla Server is a server that supports FTP and FTP over SSL/TLS which provides secure encrypted connections to the server.
Pro Kind of de-facto standard
If you're troubleshooting things, everybody will first try if it works with File-Zilla.
Con Installs junk software on your computer
The installer will install adware by default.