Which mobile device you guys recommend for the Phantom 4?

Whichever you prefer. Do you like Android or Apple better? We can't answer that for you. I can say it appears as if the iOS app is updated first, if that means anything to you.

I use both iOS and Android.  I didn't want to be married to one particular OS.  Currently I have a Samsung Galaxy Note 4 phone that works OK, but I prefer using my iPad Air because of the large display.

After reading other post about IOS vs. Android and the replies here ill go with the IPad air 2. Thanks everyone

I have a Sony Xperia Z3 Compact tablet, because for less money I get better hardware and a big plus for me - it's water (and probably everything proof, as I've dropped it 2 floors on concrete without damage ) plus extendable memory by SD card.. Had an iPad, didn't seem worth it.. But yes, in the end it's up to everyone's personal preference. The Sony is also incredibly light (have had it for over a year now and can't get tired of recommending)

Hello gfreddyunit, here is a recommended device list :

I'm using the Nvidia Shield K1, Android, it's been working fine for me.
and only $199

Samsung Galaxy Tab S2 AMOLED - works fine especially in the sun, no need sunshade.

i use a nvidia shield k1 8" android tablet... works fine and cheap also

I have a iPad Pro 9.7 a galaxy tab s2 9.7 and also a Galaxy s7 and I can say without a doubt the iPad Pro works 100% perfect while android has some bugs not to bad but not perfect.