When comparing Winyl vs Lollypop, the Slant community recommends Winyl for most people. In the question“What are the best music players for listening to high quality audio (FLAC etc)?” Winyl is ranked 7th while Lollypop is ranked 15th. The most important reason people chose Winyl is:
Winyl organizes your library by folder and not by ID3 tags. As such, your library stays organized (as long as your music folders are organized) even if you have incorrect or missing ID3 tags.
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Pros
Pro The library is well organized
Winyl organizes your library by folder and not by ID3 tags. As such, your library stays organized (as long as your music folders are organized) even if you have incorrect or missing ID3 tags.
Pro Looks great
Winyl has a beautiful interface with thumbnails for each album (if the art is in the ID tag). If not, you can easily add cover art. It also has a great mini player and that too has cover art.
Pro You can quickly and easily add music
Winyl is designed to be a fast media player with low resource usage, meaning that it takes about 20 minutes to load 67 000 files. This is a pretty good time frame in comparison to some other media players' import times. So for those with a large library, this may be a good choice.
Pro Album view
Shows albums, covers and tracks next to it, like Google Music.
Pro This program uses .cue files to split albums that are in one file
This is a convenient tool for those who may have many albums that are not yet split into separate files for each song.
Pro Super intuitive way of organizing and browsing albums and artists
You can view all the albums you have in one long list. Clicking on one of them will bring a popup at the bottom of the screen where you will see a list of all the songs on that album.
Pro Works fast and reliably
Pro Super flexible layout
The latest version has a good full-screen layout and is very responsive. Goes very smoothly from full screen to minimal player (also being a GTK+ app).
Pro Integrates with the MPRIS sound menu
This applies for most players in the "Linux world", but not for all. Therefore I consider it worth mentioning.
Pro Huge development
There is constant improvements, librem and gnome3 is possibly the future.

Pro Cloud music
Lollypop allow you to play music from the web (iTunes charts and search from Spotify).
Pro Integrates well with many desktop environments
One example being the conditional use of client side decorations (a.k.a. header bars) depending on the currently active desktop environment.
Pro Good party mode
Pro Clean, light and works very well.
The only one that can play a lot of files without to stop.
Pro Queue option lets you change what's playing on the fly
You can add songs to a queue, and then re-order or remove songs as you please. It works similarly to a temporary playlist.
Pro Online radio integration
The newest version features a nice interface for adding, browsing, and playing online radio stations. This gives you access to more music than you would normally have, which can help expand your music library for free.
Cons
Con It only shows the file name when playing tracks
Winyl cannot display the format or bitrate of the track as it plays. The user must therefore find the file in their library, select it, and go to properties.
Con GTK App
Its a GTK app so integration in other desktops is terrible it also uses GNOMEs ClientSideDecorations so it will break many window managers.
Con No equalizer
Lollypop still does not have an equalizer.
Con Good party mode
Con No In-App Volume Control (0.9.242)
It has no in-app volume control, it has to be managed through system 'Sound control/Applications'

Con Requires a well organized music collection
Lollypop will be a pain to use if music is badly tagged. The setup is a one time thing, but it can be a pain to organize a large library.
