Ipad has better screen, but regardless you will still need a hoody, just as with the Nvidia Shield, to see it outside. I like the Shield because it has an hdmi port, which you can use instead of the rc port, to see a screen mirror which I like so I can see if I'm recording or using map view, as well as fpv. Also, it has an sd slot, which Ipad doesn't, and I'm using a 64gb sd. I personally like android, because of google maps and the ability to save maps for offline use, instead of cacheing them. Also, I have rooted my Sheild, which is hard to do with Apple (jail breaking). I think the shield is just as fast as ipad, and is the better choice if you're using Cimemiser.
Completely agree, I use the Xiaomi Pad what is made in the same factory of Nvidia in China. Perfect results and super fast. Rooting and extra SD-card (up to 128Gb) is really important !