When comparing fman vs nnn, the Slant community recommends nnn for most people. In the question“What are the best file managers for UNIX-like systems?” nnn is ranked 1st while fman is ranked 13th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Works on all operating systems
Windows, Mac, and Linux are supported.
Pro Simple to use
Pro Makes finding commands *by name* easy
Pro Slick
Pro Superfast
Pro Rich set of plugins
Pro Extremely lightweight (120 kb)
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.
Pro Has a great wiki
Pro Sessions
Save and resume sessions.
Pro Supports cd-on-quit
Allows for quick switching between nnn and the terminal.
Pro Previews
The file manager has recently added support for preview hovered files using various methods.
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.
Pro Customizable icons and colors
Cons
Con No (text) file viewer
Con No explicit bookmark support for directories
It though remembers the visited directories and allows to search in this list in most-recently used order and by name.
Con Mainly for key-board-orientated users
The interface is most naturally navigated by arrows and keystrokes. The target market is software developers.
Con Has no menu bar
Hence it is not well suited for visually orientated users which find or remember commands by using a mouse and a menu. Even the fman's hero Sublime Text uses a menu bar.
Con Requires email address to download
Doesn't say what it will do with this data. It is in contrast to the new laws in Europe where only necessary information is allowed to be collected. A download should not require an email address.
Con Still quite buggy
So, for example, sorting only is remembered if triggered by command and not be clicking the table column header using the mouse.
Con Settings can't be found by the GUI
You need to know which files to edit.
Con Default dark theme
No choice between dull-dark or fresh-light.
Con No portable bundle available
On Windows only a net-installer is available.