It's not so much about the smartphone manufacturer as it is about the manufacturer of the GPS receiver chip that these smartphones use. As far as I know, both Apple and Samsung utilise GPS chips from Broadcom albeit slightly different models.
That said, I have experience using air navigation apps on iOS and never had any problems (taking into account the accuracy of a smartphone GPS cannot be sterling). The receiver was never meant to be used in that way (the device needs to be just under the windscreen to receive proper signals), but then again, it works just fine.
If you're going to buy a new smartphone, base the decision on your preference with regard to the operating system and device specifications that you would find useful. Both Apple and Samsung will serve you equally well in the air.
There are also external GPS receivers that are more accurate and approved (intended) for in-flight use. They usually connect to smartphones via Bluetooth. Look up Pooleys (or other) web shop for that.
Last edited by Wrist Watch; 25th Jul 2015 at 18:00.