When comparing cmus vs Plex, the Slant community recommends cmus for most people. In the question“What are the best media players for UNIX-like systems?” cmus is ranked 9th while Plex is ranked 20th. The most important reason people chose cmus is:
CLI makes Cmus clean, fast and minimalist.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro CLI only
CLI makes Cmus clean, fast and minimalist.
Pro Does not use a lot of memory
Cmus only uses about 15 MB. This is a very small and light media player, which is ideal for people with low end hardware.
Pro Works very well with tags from MusicBrainz database
cmus will factor in additional data from the MusicBrainz database while sorting. For example sort orders for arist or album, and the original release date for an album (in the case of a re-release).
Pro Good library structure
A lot of music players may act more like playlist viewers rather than a music library. cmus sorts by Artist > Year > Album.
Pro Fast
A lot of music players will be slow when starting if they have huge libraries, but CMus starts fast no matter the library size.
Pro Customizable keybindings for a personal experience
You can add keybindings for just about anything - including seeking (forward/backwards 1 minute, for example) which isn't supported by all music players.
Pro No mouse required
cmus does not require a mouse as it runs in the terminal
Pro Open source extensions and scripts
On GitHub you can find the official WIKI where there are a dozen extensions and scripts from color themes to a lyrics viewer and the ability to play YouTube songs.
Pro Supported on many devices
It's pretty hard to find a NAS or STB that doesn't support Plex.
Pro Accessible via web browser
A modern web browser is enough to get everything Plex has to offer.
Pro Added lots of media databases
Metadata for media files will automatically be updated by using media databases. This provides posters, movie trailers, descriptions, information about actors, etc.
Cons
Con No album art
cmus does not display album art
Con CLI only
No graphical interface is available for cmus. Everything is done through CLI (command line interface).
Con Difficult to use
Cmus uses odd keyboard shortcuts such as "C" to pause, "E" to add songs to queue, and "4" to edit the queue.
Con Can't play wavepack files
Con Needs registration
You need a PLEX account even if you use it on your local LAN.
Con Proprietary software
Unfree software.
Con No gapless audio-playback
Plex still does not support gapless playback of audio files such as mp3 or FLAC.
Con Playback error: This server is not powerful enough to convert video
More hardware requirements on Plex due to a useless/non-intuitive transcoder. When using lower spec hardware (eg SBC) Plex will not transcode or play HD+ videos. When compared to other packages (eg Jellyfin which transcodes nicely using FFMeg), Plex falls short on video playback and transcode settings to get videos to play (fastest/lightest option still fails).
