When comparing Double Commander vs Far Manager, the Slant community recommends Far Manager for most people. In the question“What are the best file managers for Windows?” Far Manager is ranked 7th while Double Commander is ranked 10th. The most important reason people chose Far Manager is:
Far Manager's interface encourages keyboard operation - all actions are easily accessible with keyboard shortcuts, you can quickly record macros for any repeatable action, there are no screen redraws if it is not necessary and that makes everything faster.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Multi-platform (Linux, Windows, MacOS X)
You can use same tool in all desktop OS environments.
Pro Source code is available (true free software)
If the developer loses interest there is at least the possibility that someone else will pick up the torch.
Pro Configurable
Lots of options allow you to configure DC the way it suits you best: Tools, Fonts, Colors, Hotkeys, Mouse, Fileviews, Plugins, Layout, Toolbars, Tabs, Icons etc.
Pro Directory Hotlist
Save shortcuts to folders. Organize them in a treeview with submenus. Define a name and sorting for each entry.
Pro Powerful tcmd-like search tool (alt+F7)
Pro tcmd-like multi-rename tool (CTRL+M)
Pro DC uses TCmd plugin API
so you can use documentation from Total Commander for writing plugins. WCX (packer), WDX (content), WFX (file system), WLX (lister).
Pro Closely follows TotalCommander UX
For instance, the 'Settings | Layout' pane is quasi-identical to TCs.
Pro Very sophisticated
Although it is lightweight and simple to use, it can do very sophisticated tasks, like copying files from directories which have a certain extension or file size or have a certain text pattern in them. Also, it's very customizable and stable.
Pro It's that good, you can replace tcmd on windows too
Pro Source code written in (Object) PASCAL
It's all a matter of perspective. I'm not for an argument about IDE's, frameworks etc, but to me that's a big plus. I think it should be a tie, it's either a pro or a con or should that be neither a pro nor a con. It just depends on context.
Pro Keyboard-oriented
Far Manager's interface encourages keyboard operation - all actions are easily accessible with keyboard shortcuts, you can quickly record macros for any repeatable action, there are no screen redraws if it is not necessary and that makes everything faster.
Pro Open source
Released under BSD license.
Pro Two-panel interface
Pro Many plugins
There are may of them, and you can write them in any languages, including Python.
Pro Editor with syntax highlighting
Every Far feature is also true for its editor. You can setup an external editor if you like, but the included editor works really well and features syntax highlighting.
Pro Easily recorded macros
Hit "Ctrl-." and start recording your boring sequence. Hit "Ctrl-." again to assign it a key. You can use Lua if you need more advanced macros.
Pro Numeric sorting option
E.g. readme-9.txt before readme-10.txt
Pro Extremely fast
Pro Offline context help
Just press F1 when you need it. No internet connection or browser is required.
Pro Themeable
Fully themeable, allowing you to change the colors of every part of the interface.
Pro Scrippting support via LUA
Cons

Con Apparently only one developer
Con Freeze after mouse double-click on directory list item
Con Much slower on Linux and Mac than on Windows
Con Source code written in Pascal language
But this does not affect users negatively. It's just programmers problem.
Con Not developed anymore for Mac
Con Can't edit files on remote FTP servers
Con Blocking operations
Operations such as copy, move, delete, etc are blocking, and you have to wait for them to complete before you can continue.
Though you can cancel the operation with the escape key.
Con Only for Windows
Con Always uses monospace font
Which makes long file names look extremely wide
Con Does not support scrolling with mouse
With plugin
Con Text-based interface
Far Manager does not use a GUI like most windows applications nowadays. This may prove difficult to use for people who are not familiar with text-based user interfaces.
Con Folder shortcuts not available in Alt+F1/F2 menus
