I was initially using my Android S7 phone and it would occasionally crash. Plus the smaller screen wasn't easy to see controls and video.
I found a iPad
mini 4 (64gb) at gamestop.com and ordered one for $224 (right!?). I assumed I'd get one that smelled like cigarette smoke and scratched, blemished but since it was going to be dedicated to the Mavic, I was going to be ok with that. If you are interested in gamestop.com you have to watch (almost hourly) because they come and go fast!
I got one that was in pristine shape, no scratches or blemishes that I can see. Looks new to me.
This is the best upgrade so far. It fits into the holder PERFECTLY and nice and snug and the display is large enough to fly the drone by watching the video. The controls on the screen are much easier to see (numbers especially). I am very impressed and consider this my most important accessory.
This all coming from an Android fan who owns about 11 android devices (tablets & phones).