It is always hard to choose one solution, especially when they look similer. We see many questions like: "What is the best navigaton app for iPhone, Navigon and Sygic?". Today Macity released a comparison video:

Navigon looks much simpler, it doesn't have some features and beautiful graphics of Sygic. By the way, do not forget, that apps from TomTom and iGO might apper quite soon in AppStore.