I tried Organic maps during a week long trip, and it was excellent!
Compared to osmand and magic earth (which I used a lot in the past), it is way more fluid and to the point. You have more important information, less overload. It loads map and POIs faster.
I only tried “on foot” navigation, and the only thing better I noticed on magic earth is the ability to choose from 3 available routes.
The search is also way better than osmand, even with magic earth from what I tried.
One key point which is available in organic maps and osmand, but not magic earth, is the ability to compute a route from A to B without GPS enabled. This is very useful when planning trips, or when using the map on low battery.
Where organic maps falls behind is transports routing. It can only show subway lines, and on my phone I couldn’t include transports in my route, it would always go on foot. On that aspect, osmand is way above all the others.
Much like osmand, organic maps lets you edit the map as you travel, a feature interesting to help improve osm, but not present on magic earth.
After trying all 3, I think I’ll stick with organic maps, and use magic earth for car navigation if I feel the routing is not as good.
Edit: seems like magic earth can compute routes from A to B without GPS, but this is not as easy to use as organic maps