J. River Media Center is a fantastic media player for Windows. Recently they have ported it to Mac [2] and an early port is available for Linux. The Mac port was still a little buggy last I tried, but a quick scan of the absolute features identified in the OP blog seem to be covered. I use it on Windows as a Media Center to serve audio/video/pics to all the devices in my home via DLNA.
What really crosses me about iTunes on OS X is that there seems to be no way to pry the media control keys loose from it, which I found perennially vexatious back when I still had an Apple laptop.
iTunes is still a serviceable player and works well for standard formats.
Vox is lightweight and can read a ton of file formats, as well as load up your iTunes library. I think you can set it to auto-load a directory at launch as well.
I used to think Songbird (now Nightingale) was going places. I remember being so excited when Songbird 0.1a came out! Unfortunately things went downhill after a couple of years until POTI killed the project and progress on the community fork has been excruciatingly slow. I want to get involved, but its hard to know where to start.
Nightingale is what I actually ended up using after I failed to convince foobar2000 on the subject of self-signed SSL certs. A little flaky on occasion, sure, but for my relatively simple purposes, it worked nicely.
