VLC Player is the TOP Media Player right now WHY ? because you can play all types of videos with different Codecs http://www.videolan.org/vlc/
Windows Media player classic.... it's playback control, sliders, display options, rendering option, MPEG2 deblocking, panning, flipping, aspect ratio adjustments...etc. etc..
3rd vote for VLC from me it can play all type of media and event it look very null but to be honest VLC one of the powerful media player.
MPlayer, Xine and VLC are top-notch media players. They all offer the same functionality with a little diffrent user experience. But once vls got merged with vlc it's advantage is now streaming capabilities over the first two.
VLC rules. i'm on a mac, and it's the only thing that can play all the silly windows files like avi's. it's nice because it can emulate dvds too.
Media player classic and VLC. if you have those two player, I doubt that you'll ever need a third one.