Offline sat nav for Android [duplicate]

Recommended software:

• I have used MapFactor, which was recommended to me on this site. It's free, uses the OpenStreetMap database (also free, with free updates) and is quite usable. You also pre-download maps so don't have to use 3G downloading as you drive around.
• Mark Mayo recommends NavDroyd:

  In addition, you need some serious storage for offline google maps. What I eventually settled with was NavDroyd - for Android, but there'll be equivalents for iPhone etc. It cost a few dollars, but not much - and the maps are all totally free, as they just download the free Open Street Maps maps, which are vector graphics anyway. It was fantastic. The interface was a little clunky to me and took a few minutes to get used to, but once I had it sorted it was brilliant - even in Siberia, Kyrgystan and Mongolia!

• dbkk recommended RMaps:

  A cheap unlocked Android phone with GPS (they start at $120 or so) plus a free offline maps app like RMaps. You don't need a data connection, but have the option of popping in a cheap local prepaid SIM card for calls and net access.

  Then you can use Mobile Atlas Creator 1.8 to download relevant maps from different sources before you go (or using a laptop and hotel WiFi while on the road).

• Other software that has been recommended include OSMAnd, Sygic and Locus Map.

OSMAnd actually seems to be the most commonly recommended of the lot.