My most used (Non-Samsung apps that come on the watch) include:
- Radar - Weather app that shows the radar for your current location. Bought on a whim and didn't think I'd use it much, but it's actually pretty quick to load and it's great to see if you're going to get stuck in a rain storm in an hour
- Navigator Standalone - Like a previous poster said, HERE WeGo is good for navigation but I like this one a bit better. You can use the handwriting function of the watch to type in locations which you can't do in HERE WeGo. Both great apps though.
- HERE WeGo - Another great navigation app, I just happen to like the above one better but can't go wrong with either.
- Card in Watch - Is this essential, absolutely not. But it's a fun magic app and it's a clever idea. You perform a card force with an actual deck of cards and make the chosen card "appear" in your watch.