Ipad
I have been running an Ipad Air 2 for more than a year now running Ifly GPS. The standard Ipad just wont work. The reflection from the screen is a problem. The Ipad Air and the Ipad Pro have laminated screens that eliminate the air space between the screen and the glass front. As for cooling, I installed a small 12v computer fan behind the panel that blows air directly on the aluminum back through a large hole covered by the Ipad. I have never had it shut down due to overheating in flight, but one time I did not bother to put the sunscreen on the dash to keep the direct sun off the panel. It took a few minutes on the ground to cool down with the fan, which is powered directly from the master bus. I fly nearly every day and here is SC it is HOT.
It was my positive experience for the last year with the Ipad that led me to the choice. Additionally, I have a backup AvMap mini-efis giving me airspeed, altitude, VSI, Attitude, and heading, as well as GPS. It will not drive an autopilot however. The user interface with the Flightview infinitely better that anything else.
Ed