To tell you the truth, if you don't mind the bare-bones look/feel, the default maemo media player isn't bad.

I'm partial to UKMP, because it works closest to how other industry media players work -- it looks cool too. I think Kagu is a little more intuitive -- although, keep in mind that it's only an audio player at the moment -- but currently, you have to create playlists in order to play music (i.e., you can't just click on a song and play it). Also, Kagu has A2DP support.

And, one must also have MPlayer on-hand for those media files which nothing else plays.

Tim