I think here wego has the best maps alternative. you are relying on another SaaS company, but it has the best response, search, map features, turn-by-turn etc. I think it's a far more user friendly app. But it relies heavily on cellular networking. So if you're traveling to rural areas in the US like I do often, the navigation just drops out. There is no option for offline maps that I've seen. So it's great for local/short trips where you have an idea where youre going or will be near major towns with good cell servie.

OSM And honestly just sucks for basic navigation. Search is terrible, it swallows battery, menus disappear and won't come back without an app restart. The worst is that you can't choose routes, you get a single shortest path route, but you can't choose alternatives. You can draw your own route, but I've had bad experience with that as well. I think OSM and is power user app, it has tremendous offline maps tools and stays stable without good cell service. But I only use it when I know I need offline navigation and I have time to plan the route out.

Both apps crap out often enough that for areas I don't know or have a map in the car for, I usually print out backup directions, or a map of the area.