>>1240466As an instructor who has been sitting in 172s for way too damn long in both instrument and vfr conditions, an Ipad mini 4 with 64GB and ForeFlight is just about right.
Get bigger and the ipad gets in the way of the yoke while sitting in your lap, and the 64gb gives you enough room for a few states worth of downloaded maps plus music and maybe a movie or two.
Just make sure to get an ipad that can run the most current iOS. I had an original iPad Mini for a good few years and once we hit iOS 10, the performance with foreflight went downhill. Like, you can't even get a weather briefing without RAM memory issues 90% of the time.
I recommend stalking Apple's refurb section online, they typically have the Mini 4s with Cellular (really, REALLY useful unless you have an outside GPS you can connect) for around $400.
In the end
>>1240480 is right. Aviation is proprietary as hell. Standard is an iPad with ForeFlight so I think it's worth it to just bite the bullet and go with that