It's also based on OpenStreetMap. It doesn't have all the bells and whistles of OsmAnd, but in return it offers a cleaner UI.
And then of course there's no beating brouter for route planning so sometimes I plan the route on PC (or the mobile site!) and import the track to Organic Maps. Mostly I don't bother though as OM routing is pretty good too.
And hey, since all of these tools rely on OpenStreetMap data, let's not forget StreetComplete for contributing! E.g. there's an easy overlay for marking cycleways.