I went for media player (10, not 11. That one's an abomination!). I play all my videos on it (with the right codecs it can play most things). Media player classic is reserved for the odd video that won't play on WMP.
I've moved to itunes for music though since I got my ipod. It just makes sense managing all your music in one place.
DVD and Blu-ray gets to go on the PS2/3 though. I don't really like the DVD software on my PC.