When comparing Double Commander vs xplorer², the Slant community recommends xplorer² for most people. In the question“What are the best file managers for Windows?” xplorer² is ranked 8th while Double Commander is ranked 10th. The most important reason people chose xplorer² is:
Full search, sync files & folders, show folder sizes, robust copy, native file viewer, tabs within panes, very configurable display, command shell, bookmarks, etc.
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 Comprehensive functionality
Full search, sync files & folders, show folder sizes, robust copy, native file viewer, tabs within panes, very configurable display, command shell, bookmarks, etc.
Pro Ability to save state
xplorer² gives users the ability to save the state, so the program will open with the same state the next time it's used.
Pro Free version available
There is a free version available, xplorer² Lite, for non-commercial use.
Pro Good all-purpose file manager
Pro Faster than most similar applications
It's hard to find a free or low cost alternative that is as quick, and stable, especially managing NTFS volumes on a remote NAS. It still freezes and chokes, just not as often as newer applications, like XYplorer, Free Commander, etc.
Pro 250+ file attributes that can be added as columns to view more file attributes
Pro Execute DOS commands
Pro Flexible search function
Search based on numerous file attributes. Search in ranges. Search inside files. Save search parameters for future use.
Pro Browse Flat to view the contents of several subdirs as if they were stored in a single dir
Let's say you are located in a given subdir that has 5 subdirs. You can see the contents of all the files located in those subdirs as if they were stored in a single dir. Very useful when you want to locate files that you don't know exactly where they are located and searching is not an option.
Pro Scrap Area where you can drop files located in different sub directories to allow you to access them instantly
Let's say that today you are going to update a letter located in subdir X, continue developing a spreadsheet located in subdir Y, review a presentation located in subdir Z, review a project located in subdir W, etc.. You can drag and drop all these files to the Scrap Area and open and work with them, save them, open again, continue tomorrow and the files will be updated in their respective original locations. No need to navigate and navigate and navigate.
Pro Supports TotalCommander plugins
Pro Copy/Move many simultaneous tasks
Can display the size in bytes of every folder listed in the current branch of the tree.
Pro Can create "tabs" of the most used sub directories that you can access with a simple click
Pro Mass rename capability
Pro Connects to network drives and cloud storage easily
Pro Lifetime license available
Pay once, get all future updates. Standard version licenses are also available.
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 Doesn't display UTF-8 characters correctly
Emojis and Japanese characters appear as question marks, for example.
Con Stagnating rate of development
Any improvements to the software are happening at a glacial pace which is making this software more and more outdated for a long time now.
Only a few minor improvements a year. User suggestions for improvements are routinely rejected or explained away. As for suggesting new features -- you'll quickly abandon all hope. Only realistic reason to visit their support forums is to read Kilmatead's posts -- for anything else prepare to be disappointed.
UPDATE (and slightly offtopic): Kilmatead seems to be no longer active on the forums, so the next best thing is xplorer2 blog which seems to often feature interesting technical topics.
Con Un-evolved
The interface is essentially unchanged since its Windows XP days, with very little customization possible. Organization of features is convoluted, with some simple ones, like individual icons to quickly switch views missing. The stagnant cluttered design can make even long-time users drop the program.
Con Distracting prompts in the Lite version
A free version of the program is available, xplorer² lite. However it is very light on features, and will display a prompt if a feature is selected that isn't available in the Lite version.
The full program is $29.95 for advanced and $49.95 for max power.
