OM and for now CoMaps are faster and easier to learn. For most people. With OSMand configurations are endless and people tend to get lost in them. Also the map data of OM is highly filtered OSM data. Meaning smaller files and a faster app.

The downside is less features, but as always ... if you dont need the absent features ... its a plus.

Now whats interesting how they both will keep it that way. My theory is when they listen to EVERY wish from random users (with other persona and user stories) they eventually become like OSMand too.