Enlarge/ The iPad Pro's display (left) is one of the best you can get in a tablet. (credit: Andrew Cunningham)
If you're interested in thorough, in-depth testing of phone and tablet displays, it's hard to beat Raymond Soniera and DisplayMate. He has just run Apple's new iPad Pro through the wringer, and he came away impressed by its color, contrast, performance in ambient light, and power efficiency. It's an improvement on the year-old iPad Air 2's display in most respects, but if you want the most accurate tablet display there is and don't care about size, it's still hard to beat the screen in the newly improved iPad Mini 4.
The full shootout is worth a read, but the iPad Pro scores points for the high contrast ratio it gets from its photo-aligned IPS LCD panel. The variable refresh rate feature, which drops the screen's refresh rate from 60Hz to 30Hz when content on the screen isn't moving, as well as the metal oxide TFT backplane on the iPad Pro also help its power efficiency relative to the smaller iPads. These are the two areas in which the Pro can beat the mechanically aligned screen of the iPad Mini 4.
While the iPad Pro does very well in other metrics, the iPad Mini 4 beats it in a lot of areas. Both the Pro and the iPad Air 2 have slightly too large color gamuts due to slightly over-saturated blues, and all iPads have slightly bluish white points that subtly affect color accuracy. The iPad Mini 4 also has the lowest reflectance of all three current iPads, meaning that reflections from other light sources are the least visible on its screen. That makes the screen easier to see in ambient light and significantly improves its contrast ratio.