After wading through several free music apps (deadbeef, mortplayer, andless, meridian, daroon, dolphin, songbird, etc.), I feel confident in saying PowerAMP has them all beat when it comes to being THE music player for Android. And this is after only using the PowerAMP trial!
When it comes to the things I look for in a music app, PowerAMP has me covered. From support for my music files (some of which are in FLAC), stability, a wealth of customization options, a small "footprint" (storage-wise), easy navigation, a pleasing GUI, and nice support from its developer, PowerAMP (seems to) have it all. The only thing I don't like about PowerAMP is that it's not free. However, I'm an enjoying it so much, I am actually thinking of buying it, and this is coming from someone who really, REALLY, hates paying for apps!