Ton of features for videophiles
MX Player impressed me with how much you can customize the experience. There are options to change the theme of the player and to enable/disable buttons in the interface.
There are even more options to enable advanced features like hardware acceleration. This comes in handy when you're trying to decode high resolution video files, letting the GPU help with decoding instead of relying on the CPU. MX Player even supports multi-core decoding, taking advantage of more powerful Android devices.
With the customization and flexibility of MX Player comes some confusion and trial and error. Some videos may play fine with hardware acceleration while others may not. You'll have to experiment with which decoder to use for specific video codecs.
Perhaps the most useful feature of MX Player is its support for subtitles. Anime and foreign film fans will love this feature. It even lets you control out of sync subtitles so it matches up perfectly with the audio.
For parents, MX Player features the ability to block kids from exiting the app and wreaking havok on your phone or tablet. Android 5.0 Lollipop lets you pin apps, making this redundant for some users. Users running older versions of Android will find this feature ueful though.
It just works
If you just want a video player that works, MX Player is great. It works out of the box and has a simple, easy to use interface.
However, if you need more customization, you can dig into the plethora of settings, which can be intimidating for some. For videophiles, having advanced options is great.
While VLC is one of the best media players for the desktop, it's mobile offering lags behind (it's still in beta). MX Player steps up and offers what VLC should have for mobile devices.
One of the best media players for Android
MX Player can be as simple or as complex as you want but in the end, it just works. All of its features are available for free with ads. There's a "Pro" version you can download as well but it's more of a donation to its developers than a requirement.
Notes
Clicking the 'Free Download' button will take you to a page on the Google Play Store, from where you can download the app.
MX Player