When comparing Harmony vs Mellow Player, the Slant community recommends Mellow Player for most people. In the question“What are the best audio players for UNIX-like systems?” Mellow Player is ranked 31st while Harmony is ranked 44th. The most important reason people chose Mellow Player is:
It is written in Qt so it requires less resources than a web browser or an electron application.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Plugins
Has support for plugins allowing functionality to be extended such as adding a new audio source.
Pro Themes
Has several themes to choose from to suite everyones individual tastes.
Pro System integration
Integrates with the operating system with support for tray icons and hooking into the audio system.
Pro Native
It is written in Qt so it requires less resources than a web browser or an electron application.
Pro AppImage
It is available as AppImage so you can easily try it.
Cons
Con Costs $10 (originally $39)
Con QML
It written in Qt-QML which ignores all Human Interface Guidelines and make the app look like a web page.
Con Not native
It's using qt5-webengine which is not much different from electron / a webbrowser.