Jet Audio is the best player available for playing all types of media files, I've been using it for more than 7 years. Still can't find better than this.
I have been using it for 2 years and I can say: it's GENIUS!!!
Cowon Jetaudio has amazing sound and video quality. When you set jetaudio's sound effects, you'll understand what is the difference between Jetaudio and other famous players. It's video renderer is the best I tested also.