Media Player Classic for me too, I tried the Home Cinema version and I use that now. CoreAVC Professional Edition (and Haali Media Splitter) for .mkv, and ffdshow, that's all And of course VLC Media Player as backup
For me: KM PLayer: Modern interface, most media without additional codecs, extremely customizable. kmplayer dot com Media Player Classic: not installation, easy to use, small memory footprint, 64 bit versions available. mpc-hc dot sourceforge dot net Vlc: multiple platforms, read DVD's from all regions. videolan dot com
winamp plays my dvd's,you have to play with the scripts,mix n match BTW i use vlc as my main,wmp as backup