I am right in the middle of researching/deliberating on this this issue now. For this season, I will only need one state, and my phone is a Samsung Galaxy. I just finished the OnX trial and used it during a scouting trip. Worked great, other than the fact that setting waypoints via a screen tap seemed imprecise. (This may have been my user error?)

I briefly considered adapting a Garmin Nuvi or an Android tablet for dedicated OnX GPS use, due to the massive screen size, but both reportedly have poor battery life, and the form factor is certainly luxurious, but too big for me.

I run redundant backup gear (multiple lights, extra clothing, lighter plus matches, etc) , and plan to buy a handheld Garmin touchscreen GPS unit and run OnX on both my phone and the GPS. The two largest (screen size) touch screen GPS handhelds to run OnX (for those new to this) are the Garmin Oregon and the Garmin Montana series. The Montana has the largest screen size, and the largest form factor. It is WAY thicker than a cell phone.

For those wanting to run a decent Garmin touchscreen as backup, a factory refurbished 600 Series Garmin Oregon runs $220-$275. The Montana series is more $$.