I use OsmAnd, but perusing both of the repos it is apparent that OrganicMaps has better code.

What I like best about OSMAnd is that you can tweak the routing algorithm without recompiling the code, as the rules are stored in routing.xml.

I use both and they're both great, but also not drop-ins for each other. OSMand has more features, but is way more confusing and quite a bit slower. So I have OrganicMaps cover my basic navigation needs, but if e.g. I want to access offline Wikivoyage travel guides, I use OSMand.

Still a wonderful and stable solution. It has some killer features as well: unlike OM, it let's you route anything. In OM good luck routing without proper GPS fix (from a parking, etc), in Osmand you can do pretty much anything.

It's insane how feature rich Osmand is, up to a point where it became a bit too complex for some.