When comparing Nemo vs nnn, the Slant community recommends nnn for most people. In the question“What are the best Linux file managers?” nnn is ranked 1st while Nemo is ranked 4th.
Ranked in these QuestionsQuestion Ranking
The most stylish among all FMs.
Pro Easily open as root
Option to open folder as root from within the right click menu.
Pro Easily open file location in terminal
Option to open a folder in terminal, which can help executing commands such as bash.
Pro Has dual pane functionality
This functionality was removed in Nautilus and Dolphin at least in Ubuntu-Gnome, but Nemo kept this option, making the obvious functionality of cut, copy and paste much easier.
Nemo can be extended to have additional features through third party plugins.
Pro Supports bookmarking
You can bookmark folders that you open often, this way you can easily access them from anywhere while using Nemo.
Pro Double pane and search by name capabilities
Pro Good networking options
Supports ftp, ssh and samba connections.
Pro Queues file operations
Pro Rich set of plugins
Pro Extremely lightweight (55 kb)
Pro Has a great wiki
Pro Unique navigate-as-you-type mode
Pro Awesome new features being added in every release
Pro Minimal configuration with sane defaults
Default options and navigation is simple to grasp.
Save and resume sessions.
Pro Supports cd-on-quit
Allows for quick switching between nnn and the terminal.
Pro Integrates with the desktop environment and opens files in the default applications
Pro Reasonably well-documented
However, it requires some prior knowledge of inner workings of Linux and there are no tutorials (yet). NNN author is making up for this by actively responding to GitHub issues.
The file manager has recently added support for preview hovered files using various methods.
Pro Customizable icons and colors
Con Changing the background color or font type for customization is not practical
You have to do it with finding and editing the relevant CSS files. No buttons, menus or sliders for such customization.
Con Incomplete mimetypes
Like all nautilus forks it allows you to run svg-files due some incomplete mimetype coverage.
Con Depends on GNOME
Depends on gnome toolkits an libraries.