When comparing PCManFM 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 PCManFM is ranked 10th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Lightweight
General use, and most operations, are snappy and responsive.
Pro Simple
PCManFM is a very lightweight and simple file manager.
Pro Can open folder as root
PCManFM can open different folders as root, this way you don't have to use the terminal to move around files for which you need root permission.
Pro Auto mounts drives
PCmanFM automatically detects and mounts available drives.
Pro Supports "quick-directory" typing
While in a PCManFM window, typing either a "~" or a "/" will automatically start typing into the location bar, allows for tab completion, and pressing Enter goes straight to the typed directory.
Pro More RAM is available for other processes, and the system uses less swap
Overall, the system becomes faster.
Pro Uses tabs instead of new windows
Tabs can practically be managed just as in a browser, so you don't end up with windows open all over your desktop. New tabs automatically start in the same location.
Pro Fastest starup
PCmanFM is the fastest GUI file manager to start.
Pro No back seat driver
Does not obstruct professional work by engrossing root warnings.
Pro Compact
Supports fast failure resolving in bulky configuration and log folders.
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 Can't extend with scripts
Unlike Nautilus and Caja, this can't extend with scripts. If script extension is added it can become a really good FM.
Con Some operations are slow
Because it tries to be as lightweight as possible and tries to use very little RAM. This can unfortunately lead to it being slow sometimes.
Con Right-click option choice limitation
You can only choose one option in the right-click menu instead of being able to select multiple at once.
Con Uses a bit more RAM than thunar
Thunar uses less RAM but you pay in slower startup and stability.
Con Directory trees can be confusing
Starts you off in a directory tree that is your home folder as if that is the very top. (Just use a single tree as it actually is and expand appropriately).