In the last couple days I installed four android gps apps, so I could decide which one I liked the best for my needs. I ended up choosing Basemap. I liked OnX almost as much, but wanted data for the whole country and $99 is too spendy for my needs.
Backcountry Navigator XE - This is very new on the scene. It ran really smooth on my phone, scrolling and map loading was butter. Sleek interface. Unfortunately it didn't appear to have as many layer types that one would want for hunting, scouting, etc. It had all the basics though, perhaps it's more of a general outdoors person app. Also, the trial/unpaid version did not let me explore many of the other features, such as tracking, etc. I'll be checking back on this app in a year when my Basemap subscription is about to expire to see if it has matured.
Gaia GPS - Trial/non paid version doesn't let you do much, so I wasn't able to change or display any other layers other then the default topo, nor test downloading offline maps. It appears that are lots of layers available if you pay. This app appears capable from reading about it, but I think it's a mistake on the developers part to not have a more full featured trial period. I didn't like it enough to pay $30 to see if I liked the full feature set.
OnX - Ran great. Great looking interface, easy to use. 7 day full trial that lets you do most things, except some layers are not available. The only complaint is I was not able to find a way to select different versions of the base maps. You get exatly one version each of satellite, topo, and hybrid. But some of the other apps (for example Basemap) allow you to select several different sources of base map content. So if you don't like the satellite image in a specific area, you can try a different one. Same for topo map versions. The other issue is the price. I'm not interested in just single state content, and $99 is far too steep with other competing products of equal capability on the market for 30% of the price.
Basemap - Mostly full featured in unpaid form, but limits the amount of layers available to display, and also limits you to a single offline map. The interface has excellent visual appeal and is easy to use. Feature set is near identical to OnX - tracking, waypoints, lines and shapes with area calculation, photo saving, built in weather data if you have signal, etc. Just as many (perhaps more) layers that you can overlay on the base map. Offline maps work excellent, can select as many layers as you want, and are available in full or customizable resolution, and for any area that you select. There is a social media feature that allows you to share content. That's cool if you're into this, but I'll likely never use it. I suspect that Onx and Gaia also have web maps like Basemap does, but I've only used the Basemap one. It allows me access to all the same layers and features as the phone app, waypoints, lines, tracks, etc all sync between the phone and computer automatically.
Anyway, in summary I like Basemap just as much as OnX for the 1 day I have used them. For the cost, Basemap was an easy choice for me.
Based on google play store's info descriptions:
-Onx came out in 2013 and has around 71k+ downloads per year average.
-Gaia came out in 2010 and has around 50k+ downloads per year average.
-Basemap came out in 2016 and has around 25k+ downloads per year average.