Openstreetmap vs Geoname

Who provides better coverage, accuracy and Quality among Openstreetmap and Geonames? What is suitable if I want to have a postal code based lookup (geocoding)?

According to taginfo there are about 400.000 postal codes (of which many may be the same) in the OSM database, that’s very low coverage. Geonames does not appear to have a high resolution (only up to place name), so both are not ideal.

Thanks Lambertus. Can you suggest any other tool for the same which provides assured data quality and good coverage? I have read about Gisgraphy, but then again it uses data from Openstreetmap and Geonames.

I don’t know any better source then Geonames + OSM apart from commercial packages (from e.g. TeleAtlas and NavTeq) and possible other (illegally acquired) copyrighted datasources. So I can’t help you any further then this.