@Hisham The ‘best’ is difficult to say: the one that can do the most is certainly OSMand. Organic Maps is easier and is sufficient for most purposes.
With both you can navigate as well as edit/add OSM data.
Car drivers also like Magic Earth, which is OSM-based and without trackers, but it's not #FOSS .
#OSM #OSMand #OrganicMaps @Organic Maps