thanks for the reminder - I forgot to share my information about Beyond Compare.
I see.
The capabilities of Beyond Compare (BC) are comprehensive, so even with a clean interface, you need time to learn.
I work with BC since many years, therefore my comparison will always miss some "not so obvious" pros of other tools. That's why I'm interested in other people's experience with these.
A good folder/file comparison tool is the swiss army knife needed every day, for many tasks. Therefore I want a good, powerful tool.
Some features of BC (the order is no ranking):
File format filters: You can place any processing between the original file and the display. For example, PmWiki (a CMS I'm using) encodes line endings in page files. With a simple SED/Perl/whatever-script, you can convert it easily to readable format. Of course, filters for standard formats are shipped with BC or ready for download: PDF, Office and so on. Sorting of files (before comparison) is built-in.
Include and exclude filters: Tell BC which files and directories to process or ignore.
(S)FTP with real editing capability on remote files (Ultra Compare uses a local copy being uploaded after editing, not so elegant).
You can edit directly in the comparison windows. This way, you can adjust line wrapping or have even more control while merging changes. Also great for working with configuration files! Compare the config file with a template and adjust the settings interactively.
Archives (gz, zip...) are handled like folders, you can move files between archives etc. Of course, you can also edit files in archives.
Processing of file metadata: Copy time stamps of identical files from one side to the other. Handle permissions and so on.
Viewers for many file formats. For example ID3 tags in mp3 files. Of course binary data, csv/tsv and so on.
Powerful picture comparison with stretch, zoom, pan, many difference modes...
Scripting / batch processing.
And much more I don't recall.
The development of BC is a bit slow in the last years, but that's a luxury problem. The upcoming version will support WebDAV, Subversion and Dropbox. Maybe we'll get handling of file renames/moves some day. Or IMAP support, MTP
Oliver