I would argue that WinAmp and XMMS where the last good audio players. Why is it that modern music players think that the need to do library management, why are they fullscreen applications?
We need to start maintaining winamp and the clones again.
For pure mp3 playing, foobar2000 is like winamp except still getting updated, with less ugly (more OS-conforming) UI. For even more simplicity, there's no reason you should need a separate app for mp3s and movies, and mpc-hc is the best no-nonsense media player.
I think there is a reason to keep audio and video playback separate, because you approach them differently.
When you are watching video, it's usually where your attention goes, whereas listening to audio is something done "in the background", while your attention is elsewhere (reading, writing, playing a game, or even cleaning the house).
Therefore to me it is obvious that an audio playing application should behave like a good butler - readily available when you need to e.g. change the playlist, but invisible otherwise - and I would compare a video playing application to a live entertainer.
A video playing application should of course also get out of your way so you can focus on the actual video, but there is a subtle difference nevertheless.
The author of foobar2000 even made another music player that is much simpler, great for people like mrweasel, I think: https://perkele.cc/software/boom
In my opinion, it is the best audio player and available for almost any system. Can do things you would assume are basic features, but most players fail to implement. Like mirroring stereo sound through all you other speakers you might have.
I don't mind having library management, and I would love to have a Linux clone of foobar2000. Nothing else has its tag management and search/sort capabilities.
I put lots of custom tags in all of the tracks I've ripped, downloaded, or recorded live, and I have yet to come across a Linux music player that allows me to search them or sort by them.
Clementine comes close, but not quite close enough. Maybe I need to get some Copious Free Time and rip into its sources.
It basically works perfectly for me, though it can take a bit of setting up. The only downside I'd say is that drag and drop from outside foobar is a bit wonky, you can't always drag and drop from a native file manager (though it always works if you drop onto the status bar instead of the playlist). You can also bypass the wine audio stack: https://www.head-fi.org/threads/foobar2000-on-linux-how-to-b...
That was a late (and welcome) addition that's still optional - you can use Winamp 5.x in classic mini-player mode, with nothing but the queue and playback controls, using your file system to manage what you're playing. I don't, apart from ephemeral files, but apparently it's a thing people like.
We need to start maintaining winamp and the clones again.