I have both an iPad Pro 10.5" and a
CrystalSky Ultra. There are definitely pros and cons to each which I why I actually use both rather than one or the other. If you get the new PolarPro Flight Deck, not only is it the best mount I've ever used, it comes with a plate for
CrystalSky as well as a tablet holder.
iOS apps are better -- plain and simple. Android is a cheap, knock-off version of iOS, and that's really my chief complaint with the
CS. To confound matters, DJI doesn't keep the
CS version of GO 4 as up to date as either the iOS app or the standard Android app. That said, the
CS really stands out in terms of screen quality and brightness. iPad Pro doesn't even come close. While you can use Litchi on
CS, using multiple apps on the iPad is just easier to deal with.
CS doesn't have direct access to Google Play so that makes it more difficult to add additional pilot apps.
Bottom line, if you primarily use GO 4 and can live with a lag time in upgrades, the
CrystalSky provides the absolute ultimate flying experience.