I don't know about mplayer being more stable then xine-lib or vlc In fact I've always found it to be the opposite. That is just personal experience though. I'm not a big fan of vlc either but it does seem to have more flexibility then the others. My personal preference has been actually xbmc which seems to be more stable then all the above.
I may be wrong but doesn't xbmc use mplayer as its core to play media files?