I think OSM is way way better. It has every little path in the hills I walk. On Google Maps I'm just walking in a featureless green blob. OSM even has unofficial trails that are no more than a worn-down line in the brush.

Maybe for cars Google is better but I don't use those. But even there I see really detailed stats.

OSMAnd is a really great full featured mapping app. A real tool that you can configure in detail. And Organic maps is more simple and quick like Google maps.

There's just two things I still need Google for: most businesses don't bother keeping their opening hours etc updated on other mapping services, and in my city they have live data on the public transport network. This should really be mandated to be offered to open street map too.