I have all 3, though I have not used AllTrails in a good while.
OnX Backcountry: You can often get it for quite a bit cheaper than OnX Hunt as they runs sales on it throughout the year. Trail info, map functions are the same, though you don't get unit info or the hunting specific icons such as elk, sheep goats, wallows etc for the waypoints. I personally only use OnX Backcountry for ski touring as the winter overlays and integrated avalanche forecasts info is useful and convenient.
OnX Hunt probably wouldn't offer any real advantages for the purposes of one hunt in the middle of public land, but for hunting different species in different units, its absolutely worth it.
Ethically, AllTrails is owned by Outside which does a good amount of public land advocacy. OnX is independently/privately held with also a good track record of public land advocacy, though some amount of that is hunting specific since OnX Hunt is their flagship app. Their CEO sits on the board of the Theodore Roosevelt Foundation, for example.