FOSS options built on OpenStreetMap: Organic Maps (fast, simple, offline, turn-by-turn), CoMaps (a community fork of Organic Maps), and OsmAnd (more features: offline maps, voice navigation, plugins, a steeper learning curve). All work offline once you download a region and don't need an account. The thing you'll miss from Waze is live crowd-sourced traffic; none of the FOSS apps really match that yet.