When it comes to using your phone for GPS navigation, I don't think that the operating system is the big issue. The two big systems (EasyVFR by PocketFMS & SkyDemon) both have apps for both.
The EasyVFR by PocketFMS app is identical on both operating systems, and I believe that the SkyDemon system has only slight differences.
The quality of the GPS receiver won't be much different too, but one thing to note is that on Apple devices you can't put it into flight mode and use the GPS receiver. You can on Android. But that's not really much of an issue.
The more important things to consider are:
1. Screen size (the bigger the easier to see and use)
2. Power! Phones batteries aren't really designed for having the screen on in outdoor lighting for a long time, with the GPS running. The battery probably won't last much beyond 90 minutes. So you really need some sort of external power.
dp