My go to video player is VLC. However lately ther have been a couple viedos that I have recieved that dont seem to run very well with VLC yet work fine in Windows Media Player.
When I say dont run very well I mean thay get a pixilated blured image, the sound is still fine and synced but the image is all messed up.

The movies come from good sources and are always DVD rips or BR rips.

MPC-HC (32bit and 64bit) as some MP4 videos don't work well with Winamp and WMP is OK for AVIs. That's what I use. MPC-HC is also ideal for MKVs.

MPC STAR plays just about everything* I mainly download 720p and 1080p so, my video files are 99% mkv. I use MPC Star to watch avi and mp4 as well, no issues mate. It's freeware! VLC Player isn't great at all btw.

VLC and Media Player classic bundled with K-lite codec pack...

VLC
Tried MPC Star, got an unrecognizable error in the first five minutes of the movie that shut it down, played the same movie on VLC, and it went through without a hitch.

Windows Media Player-UMPlayer- VLC

VLC, is there another one out there

Media Player Classic (K-lite Mega Codec Pack)