It depends on hardware usage (Keyboard or mouse) at the time. But what i generally use is
Audio: Windows Media Player, VLC
Video: MPC-HC (K-Lite Codec Mega), VLC
For keyboard controls, i use MPC-HC as it has the best keyboard shortcuts/keys IMO. I specially like the features to play the next file in the folder shortcut, so even if i didn't create a playlist i get to play all the files in a folder & left click on video to pause/play. Respectively i use WMP as it is compatible with my keyboard media keys.
For mouse controls, i use VLC as it has the best mouse controls IMO. I specially like the step-forward & step-backwards buttons in the toolbar.