You should use a tablet or smartphone with a minimum of 3 GB Ram and Quadcore Proz., otherwise in most cases, the video-delay and reaction time will be not the best. The sensitivity of wifi is not importand, because the devise is near by the controller. If a tablet, a built in GSM for I-net connection can load maps you need on different places. Last but not least, the brightness and resolution of the display is one of the important things ..
I prefer Android - using a galaxy tab and S6 Smartphone - not the best, but for me it`s still okay ...