According to the latest test results from Displaymate, the iPad Mini has a screen that is noticeably inferior to the screens found on the Fire HDX and this year's Nexus 7. While the latest offerings from both Amazon and Google scored high marks in the study, Apple's tablet "comes in with a distant third-place finish". DisplayMate evaluated the devices on a wide array of fronts, including calibration, sharpness, brightness, and color gamut. They found that while the tablets packed about the same density of pixels, the Fire HDX and the Nexus 7 were both able to display 100% of the color gamut but the iPad Mini was only able to show 63%.
The Mini was also dinged for being more reflective and for having a lower maximum brightness and contrast. And finally, the iPad Mini is also less energy efficient, with the Nexus 7 having the most efficient screen of the three.
It's not clear whether the Fire HDX or the Nexus 7 came out a head (it looks like a tie to me), but it is clear that both Amazon and Google have improved the screens on their tablets in a very short while.
In fact, if you discount the first Kindle Fire as a rebadged BB Playbook then Amazon and Google bested Apple after only released a couple 7" devices each. That shows a remarkably sharp ability to learn and adapt, and it should be a concern for Apple.
These test results come only a couple weeks after the iPad Air was dethroned as the best large tablet screen, leading me to echo DisplayMate's comment: "Apple was once the leader in mobile displays, unfortunately it has fallen way behind in both Tablets and Smartphones. This should be a wakeup call."