I personally use OsmAnd on mobile (available exclusively on Android), but I’ve taken to using CoMaps on desktop. The menu UI on the right leaves something to be desired, and it’s not nearly as powerful as OsmAnd; however, the map itself is rendered well and easy to navigate, the search and navigation functionalities work well, and map updates come frequently.
To me, it’s the best desktop maps application provided OSM has decent coverage in your area. (If not, I could go on for thousands of words about why you, yes you, should contribute.)
Here’s an example screenshot of a walking route between two nearby locations:
Context for those using Organic Maps: CoMaps is a fork of Organic made by former Organic contributors that has been active for over a year now. It’s generally accepted as better than Organic. This is the open letter they wrote to Organic airing their grievances.
Why YSK: Offline maps are a great way to safeguard your privacy and don’t require much storage space. Likewise, using OpenStreetMap is a great way to maintain digital sovereignty from giant corporations.
That actually is dumb design. I suggest using the F-Droid version which gives unlimited map access. I never use more than the base 7, but (apparently) not being able to change what those are is silly.