All of the map companies source a large portion of the data that ultimately ends up in their maps. Google has a great mapping platform but the differences between others aren’t as great as you mentioned above. Microsoft/Windows/Bing all use Nokia Maps (formerly Navteq). Yahoo, Mapquest, and Garmin also use Nokia Map data to create their product. Each map is essentially made up of two types of data; that which contains information regarding the road network itself (speeds, road connectivity, freshness of that information) and that which contains information about the POIs (Restaurants, addresses, the things you’re trying to get to). Google is best because they have a map backed by a superior search engine than the others. They’re all sharing data.