I've been using Plug for about a year, and I have to say it's my favorite player. The past month I've also started using SoundMate and Radiant, but I still feel that Plug is the smoothest and least in the way.
I've been a hypem fan for 7 years. Take it from me, it's the BEST.
My company's UX even riffs off of theirs (with an unrelated focus)