The iPad Mini's screen is the best of the three media tablets reviewed here, with brighter display and better tonal range. By contrast, the Kindle Fire HD and Nexus 7 were both a bit dark and muddy. A full-size, third-gen or fourth-gen iPad screen has even better color range and details, though honestly you only notice the differences in nature films and sci-fi epics, where high-def images are accentuated. Your typical comedy film or TV show appears the same on both types of iPad screens. A bigger issue is the reflectivity of the iPad Mini's screen, which even in cloudy daylight skies causes a reflection of your face to be constantly in view.
The Nexus 7's video display was the most muted, even with the screen brightness turned up, likely due to its yellowish color balance. It too suffers from an excessively reflective screen.
The Kindle Fire HD's video playback had a bit more life to it than Nexus 7's, but it wasn't quite as bright or as well-balanced as the iPad Mini's screen. It also suffered from periodic stutters during playback, even of video stored on the device. Neither the iPad Mini nor Nexus 7 had playback stutters. I found the Kindle Fire HD's screen overly reflective, too.
Audio playback. All the media tablets support standard audio jacks for private listening on the headphones or earbuds of your choice. All three also support Bluetooth audio streaming, and the iPad Mini supports Apple's proprietary AirPlay streaming over Wi-Fi networks to compatible speakers or, via an Apple TV, to stereos and TVs.
For direct audio, the full-size iPad has long suffered from having a mono speaker, though one with good clarity and tonal balance. The iPad Mini adds stereo -- and wins hands down. You can crank the iPad Mini much louder than the other two tablets, without the distortion the Kindle Fire HD has at maximum volume.
The quality is good enough for boom-box-style use, such at a party or conference room, though at maximum volume a flatness creeps in, likely due to the iPad Mini's thin chassis. To optimize the audio, the iPad Mini's Settings app has equalizer preselects you can choose, but no tool to set your own EQ settings.
Sound from the Nexus 7's built-in stereo speakers struck me as tinny, muddy, and hollow, even with bass boost on -- it was grating to listen to. It's also the quietest of the three media tablets. There's an equalizer option in the Play Music app where you choose an EQ or set a custom EQ, but it's not intuitive to use. I could make the audio sound less tinny, but I could not eliminate the hollow tone no matter what settings I tried.