A very good navigator is MapFactor Navigator Free. As the name suggests, it's free (as in "free beer", not "free speech") and it uses Open Street Maps (free as in "free speech and beer"), directly downloadable by the application menu.
As of today it's still in beta, but I tried it and it works well, comparable to if not better than Sygic, which I was using before.
MapFactor Navigator is on Google play.