I played around with Basemap last year. I didn't do a true side by side with OnX, but as I've used OnX for forever and I didn't plan on a review, I didn't see the need.
Basemap:
-The 3D Earth feature is very cool, but only on iOS, which is dumb.
-Very comparable with OnX on features: unit boundaries, ownership, topo, sattelite
-Unit info pops up in screen. This is a really nice feature. Its built into the app and you don't have to follow a link like OnX.
-Has layers not of hunting nature that OnX Doesnt: flood zones,
-Screen view is less cluttered but access to layers and tools seems clunky
-GPS signal is on the screen so you can see immediately how its performgin.
-Top bar of screen is black so you can easily see elevation. In OnX the map behind can make it hard to view.
-Live sharing of location with friends is nice, but potentially problematic in Montana where that could be viewed as electronic comm.
-info screens that pop up are better layed out than Onx, but still has same info.
-$29.99/ yr ($9.99 more if you want the desktop version.)
-includes all the states.
-Gohunt similar sorting feature, could be nice.
OnX:
-many more layers that Basemap doesnt: roadless, RMEF,NWTF, nautical charts, batymetry, river stage,
-Instant weather conditions on screen is nice.
-Can import data; can't do that with Basemap.
-$99.99/yr for all the states. (discount codes abound, that drop that to $80).
-Desktop is included.
If I were just starting out, I would still go with OnX for hunting. Most will be porting over old data, so being able to do that is important. There are more usable layers with OnX. It seems that OnX is adding more to the app and working hard to bring new content. I can't say the same for Basemap, but haven't been following it either. I also didn't see any accuracy issues with either.
@elkhunts: your one post robs your comment of credibility and smacks of smear. Clerical issues abound in beuraucy, and are fixed as they are found.