MPC-HC is still better than PotPlayer, change my mind.
I use MPC-BE with K-Lite Codecs, with included LAV Filters and madVR. Gives me some nice looking videos.
Also, if you're looking for a nice free file manager for Windows, I recommend Far Manager.
Yes, it is a CLI program, but don't get scared by that fact. It's highly customizable and expandable by plugins, which can make it also a registry editor, software uninstaller, or even an audio player. And keep in mind that you will have to learn a few keyboard shortcuts to use the program effectively. But after that, you will manage your files with a much, much higher efficiency compared to the default Windows Explorer.
And to accompany Far Manager, I'd recommend using
ConEmu. It's a console emulator, which enhances the looks and functionality of the console terminal, as well as Far Manager, giving it a few more useful features, such as thumbnail view, custom backgrounds and more.
Some more recommendations:
Keypirinha - A very useful fuzzy search launcher, which after some configuration is a very useful and snappy tool for quickly launching a program, converting units, currencies, doing basic calculation, translating phrases and more.
Barrier - A FOSS implementation of Synergy, which allows for using multiple systems with a single keyboard and mouse. Very useful if you're working on a PC and a laptop simultaneously.
TeXstudio - A great LaTeX editor, which makes the best looking documents around, better than that stinking Microsoft Word or it's free derivatives. You'll need to learn some basics of LaTeX, but it's not too hard and worth the hassle.