I'm a data geek, and have probably used every mapping app and service out there. I reviewed Basemap last year, and didn't think it was ready for prime-time. It's come a long way. It still has a few glitches (particularly in the Web piece of the app), but it now does basically everything OnX does, and better in a few areas.
I bought my first OnX subscription just before hunting season started a few years ago. That made sense at the time, but also means my renewal comes up every year just before hunting season starts. This year I'll be dropping OnX in favor of Basemap.
There are a couple of "winner" details for me. First, where OnX is $29.99/yr for one state, Basemap is the same price for all 50 states. And for those that only use the map a couple months a year, they have a $4.99/mo option. That's a winner for me, because I tend to only use these apps in October and November. The rest of the year I use Locus Pro, which is much more powerful for general topo mapping and hiking than either app.
Second, the Basemap download mechanism is MUCH better. With OnX, to get high-res data cached offline you have to scroll around and download each tile one at a time. With Basemap you can do that all at once. That's a big time saver if you know you're going into a unit where you'll be roaming around a lot (which I do).
I don't really think much of the "journal" feature. Most hunters I know (including me) are pretty cagey about sharing overly-specific details about exactly where their honey-holes are. I can't imagine wanting to share all the notes I take to Facebook (which I don't even use), let alone with other people in general. But it's easy to skip it if you don't want to use it. It's just a shame they focused so much of the app's real-estate on that feature.
The track recording is also better now than OnX IMO (particularly in what you can do once a track is done/saved), but still not nearly as good as Locus. Locus has features like being able to quickly pick a point (like a glassing spot) on a route you pre-planned, and showing bearing guides and distances to get you there. That's a critical feature for me for things like quickly getting to glassing spots, retrieving trail cams, etc.
Obviously Locus is staying in my toolbox, and to be clear, I'm not saying OnX is "bad." The way I would describe it, Basemap is now "as good as" OnX for my personal needs. I plan to switch this year based on price and ease of offline downloading. YMMV.