Best Smartphone for GPS?

First off, I'd look primarily at Samsung models as if I understand it correctly, they're becoming the only ones who still do removable batteries. You can get an add-on battery boost thing for other phones, but IMO it's just better, simpler, lighter to carry spare batteries and swap 'em at need. Well, there is the downside that you need to completely turn off the phone and then boot it up again to replace a battery, and maybe the same to recharge it in towns.

I'd also look to see that your phone gets the Russion Glonass satellites.
http://en.wikipedia.org/wiki/List_of_smartphones_using_GLONASS_Navigation

You don't need the absolute fastest, biggest, coolest, and most expensive phone. I'm currently using a Samsung Galaxy Ace 2, and it's just fine for that sort of use. A sort of bonus to not getting the most expensive option out there is that it's that much less of a pain if you damage, break, or lose it along the way. In three thru-hikes my smartphones have come through just fine, but … it's certainly always possible.

With a Mojo Refuel charger, you can swap out batteries for your iPhone as well, FWIW.

http://www.ibattz.com/products_power_refuel.php

Tom Harrison maps are available as an ap on Android.

"Tom Harrison maps are available as an ap on Android."

A few available on iPhone as well.

I also use the iBattz mojo case on the iPhone, basically giving you the switchable battery you desire (it comes with 2 batteries).

This case and two batteries got me through 4 days in the Sierras, I only used one battery, and the second battery recharged a friends phone. For GPS Apps I used Gaia and Topo Maps.

I used the SIM lock trick to just have GPS on, as noted here: http://adventurealan.com/iphone4gps.htm

OP,

I can't speak as to which phone works the best as a GPS but I thought I'd share how I use my iPhone and post the weights so you have something to compare it with.

Some background on how I use my phone. Often times my AT&T iPhone 4s is my primary camera (albeit not a great one). I'll leave it in airplane mode but occasionally turn that off just long enough to plot a GPS coordinate with Gaia. I leave it on 24/7 and never remove or disable the SIM card.

None of my backpacking trips were all that long last summer but after four days, I still had 1/2 charge left on my iPhone battery. My phone was less than a year old so the battery hasn't begun to deteriorate and still holds a charge fine. I purchased a Concept Green battery bank for no other reason that it was less than $20 at Fred Meyers.

.

Specs:

Capacity 3600 mAh

Output options:
1. 5V 1A (option I use for iPhone)
2. 5V 2A
3. 9V 1A

Weight for battery bank, iPhone charging cable, and bag 4.9oz.

With the iPhone 4s' battery rated capacity being 1400 mAh and allowing for 30% loss during transfer, I can fully charge my phone from empty almost twice (40 mAh short) in theory. In reality I don't know because I don't let my phone go completely dead before recharging it.

I've yet to take it on an extended trip this but at some point this winter, I'll forward my calls to my other phone and try to recreate the field environment by keeping this phone in airplane mode, take 50 photos and 10 videos per day, and plot seven grid coordinates per day to see just how far I can take this system. Based on my limited experience so far, I suspect it's in excess of 1.5 weeks. The reason I bring this up is that you can try this on your own and compare weights to see if you are better off keeping your iPhone than buying the Samsung or whatever

Traditionally, Motorola phones have the best gps radio. I have been using a Galaxy S3 for day hiking and overnight trips for better part of a couple years. I would rate the gps radio as just "OK." I will say that I do like BackCountry Navigator app a lot, so check that out if you get an Android phone.

My biggest disappointment with Android phones, and usefulness as a mapping/gps tool, is in battery management. There are SO many behind the scenes processes that gobble up battery power it is hard to deal with. Even running in "Airplane Mode" drains my battery MUCH faster than my wife's iPhone 5.