I used to be a longtime user of Mapfactor Navigator as it is a very fast and at the same time a "light-weight" app for your phone/android unit, but they create their maps by hand and these sometimes contain errors, which gives you errors in routing.
I currently use OsmAnd+ for hiking/bicycling and Magic Earth for car navigation. The latter also because it has (free) traffic info and can be used to create multi-point routes though not as good and easy as OsmAnd or Mapfactor Navigator.
Because of its profiles (which are extremely buggy and unworkable in the current 3.5.5, but which work correctly in the to be released 3.6 version) I also use OsmAnd now for caravan because it routes better thanks to those profiles.
The maps of OsmAnd are more detailed than any other map. The 2nd reason for the big map files is, is that they are uncompressed while all the other apps use some compression algorithm like zip, gzip, lz4 (extremely fast), etc.
It would be a big bonus for me if OsmAnd would compress their maps as well (with for example lz4). It is not only about size on SD-card, but using a fast decompression algorithm increases the speed at which maps can be read: reading a small file from a slow disk and uncompressing it in fast memory would be beneficial for overall performance.
Harry