@bradrh How did you decide meanwhile? Also my Garmin is about to fall into pieces, and also I am looking for a customizable map on Android.
While trying to learn OsmAndMapCreator, I stumbled upon the utter lack of documentation, and quite a lot of bugs which are well known, and you have to use some specific workaround for them…
I found out how to integrate elevation contour lines into the map and get them displayed, but most features are more complicated (e.g. treating highway!=track with import=yes like highway=road, or displaying unpaved major roads differently from paved highways, and also treat them differently in routing).
The Garmin world was great, due to the dedicated support by Steve and Gerd whom we are indebted to thank.