I've been very picky about music players over the years. Basically for decades (well, maybe not that long) it was PowerAmp, ever since I had my HTC Hero on Android 1.5.
Then when I got into the whole Open Source thing, I chose Musicolet and loved it, even donated to the author.
Sadly, on my latest phone which seems to have incredibly strict memory/power settings, I had to stop using Musicolet. The phone would kill the player a sing or two into listening no matter what tricks I would use to try and stop it happening.
Now I'm using Phocid which has never been killed while in use.
And I keep all my music in finders, correctly named and tagged with MP3Tag and MusicBee because, you know, Autism. ๐