OsmAnd is a heavyweight with more features, including an advanced OSM editor, trip recording, Mapillary street view, and other plugins, for those that need them.
Yes, Organic Maps is a fork of Maps.me. The original Maps.me was acquired by Daegu Limited, a subsidiary of the financial services company Parity.com, and they stopped publishing source code afterward.
What I'd really like is for all OSM apps to agree on a place to store the offline OSM data.
I don't mind having multiple navigation apps with different strengths/weaknesses but I don't want to download several gigs of offline maps for each app I might use.
In my experience, where the open source apps often come up short is not really mapping but rather turn by turn navigation. The first, most obvious indictor being the voice prompts. If they sound like a bad video game from the 90's, you can bet the directions are equally flawed/bad.
For me, the biggest issue is business information.
I rarely use map apps to find directions, except while hiking or having a stroll, in which case, yes, OSM is superior.
Most of the time, I need to either:
A) Look up a certain type of business, check its opening hours and (if applicable) menu, phone or message them to ask any questions, and only then drive to the business in question
or B) get somewhere without a car, and figure out the fastest route by public transportation without having to find multiple different websites and cross-reference their respective timesheets
These activities aren't really the job of a mapping or navigation map, they're the job for a data mining app.
OSM often has better paths than Google Maps, but Google's commercial and transportation databases aren't going to get beaten by any open source service any time soon.
