If you were to contribute directly to OSM, the obvious choices appear to be
- iD - an online editor integrated into OSM
- Vespucci - an Android-based editor
- tutorial on selection and creation
- See also amended documentation on selection and creation here: https://github.com/bjohas/osmeditor4android/blob/master/documentation/docs/help/en/Introduction.md
- JOSM - a cross-platform java editor.
However, for many non-technical members of the public, these are too complex. If you wanted to get non-technical persons to provide data, what would you do? See Maps/Collecting_geodata_and_mapping.