Not sure if it’s available for OSX, but I really enjoy mpd + ncmpcpp.
Highly configurable, you can have it display album art and it continues to work when you close the terminal.
I also like that you can control it from your smartphone.
Second to that Foobar would get my vote.
Have you tried Clementine? I’ve been using it for years. Available on Linux, macOS & Windows.
Fubar 2000 is pretty good. And it’s free.
http://www.mediamonkey.com/download/
I knew I was forgetting something… I have played with so much software that I forget stuff.
Foobar does show album covers, but you have to customize it yourself to use the Album Art Viewer.
In View -> Layout -> Create Scratchbox. You can mess around creating a layout you like and then hit apply.
If you’re too lazy you can use mine: [Link is dead]
Have to drop the component into the component folder or install it from File -> Preferences -> components -> install. Then just double click the .fth
If you end up using it and need help with something let me know.
I gave Tomahawk a shot and found it to be shitty.
Yeah, it’s kind of buggy and I’m not a fan of how it continues playing for a bit when the stop button is pressed.
Really
Is Foobar that basic on Mac ? I’m not sure whether to recommend removing foobar or macOS first now … 
Does it even support importing premade themes ?
I tried and didn’t find anything.
If you find a way to do it, feel free to let me know.
Yeah on the dl page it says:
“It is by no means complete and is not currently under active development.” So I’m guessing the theme features aren’t in the release.
I wish I could help more, but don’t have a mac on hand, sorry. 
Just imagining the hardware compatibility issues is giving me cold sweats 
I’ve resorted to using MPV for playing FLACs, Clementine uses 10%+ CPU all the time, Foobar is nowhere near complete, Tomahawk was also resoruce heavy.
Yup, exactly… xD
What is MPV
It’s an excellent, yet barebones media player. I’m not sure it’s what you’ll be interested in, but it’s worth checking out at least.
MPV is like VLC, but more lightweight and does just play everything pretty much perfectly, without any other features than just play the thing you pressed on in your file explorer, however. So as a music player/library manager for like 2k music files… no, thank you very much. But it´s a great replacement for VLC for the most part. VLC can do other things like converting and cutting videos even, if you need to and lack a proper editor at the time. So for that reason, I keep VLC around as well “just in case” it might be doing something I might eventually need that MPV does not, but I really only use MPV now. Not like it costs anything to install both though.