MPV vs GOM-Player

When used with youtube-dl.

Everything MPV needs to play media files is contained within which means no outside codecs are needed.

Click to open files and get Video with sound (and passthrough of codecs like DTS etc) for a perfect cinema experience. Works okay for many files.

Default window is not much more than a title bar - and if you drag/resize the window it resizes the video and leaves no empty areas. There is no visible control or display unless you use mouse/keyboard over the window.
This is the best player to use unless you're going for a media center (then use MPV based Plex Media Player to display and play the Plex Server library).

Always up to date, rapid development.

Intelligently caches livestreams and enables jumping within the cached stream.

Automatically adds files with similar name to playlist

In contrast to some other popular players out there, the GOM Player skin engine really works out. Skins on GOM Player feel quite natural and everything is still very responsive. So even skins in use, the whole player doesn't feel bloated.

Something I did not encounter often is the fact, that GOM Player has some magic trick up its sleeve. It mostly allows to rename the currently playing files and sometimes I can even move them. I cannot really tell how that works, but it does (playing from UNC network paths here (ntfs, windows)).

Whether it's switching audio channels, aspect ratio, playback size. All can be done easily via context menu or keyboard shortcuts or even mouse clicks if configured.