When comparing nnn vs Vifm, 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 Vifm is ranked 12th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
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
Pro Allows you to stay in the terminal
Since it runs in a terminal, it may live within ssh sessions, tmux/screen sessions, etc.
Pro Nice Themes for a terminal app
Vifm has a lot of good themes that you can easily grab from the main site and use with the :colorscheme command.
Pro Configurable
You can easily configure almost all aspects of vifm by just editing the dotfile which is pretty easy is you are comfortable with configuring apps.
Pro Great integration with vim
The vifm.vim plugin allows you to use vifm as a powerful filepicker for vim.
Pro Default key mappings will be comfortable to vim users
Vifm uses vim-esque key mappings. Makes for extremely efficient and---perhaps more importantly---intuitive interactions. The key mappings can be changed.
Pro Dual pane
The dual pane nature of vifm makes copy paste and moving files from one folder to another super easy.
Cons
Con CLI, default interface very simplified (supports mouse)
Con Useless for non-vi users
Even to quit one has to use ":q".
Con Very high learning curve for newbies
Con Can only be used in terminal
Vifm lacks a standalone GUI option.