I just recently started using Mapy.cz, first impressions are positive but not sure yet if closed streets caused by for example road maintenance are up-to-date. Second one i installed yesterday is 'Organic Maps', based on Open Street Maps data. From what i read online i got the impression its more focused on hiking and biking but routeplanning for car travel is supported. Not used enough to have relevant experience.
I can confirm that organic maps is not that great when it comes to long car trips because it calculates all locally (I think)
A better alternative would be magic earth :)