I did a test with different Geocoders (Google, MapQuest, Bing, Yahoo, Nokia). Google was lightyears ahead of the rest in my test. It was for the Netherlands, though.

The netherlands is a different beast when it comes to Geocoding since each postcode only corresponds with around 10 buildings all very close to each other. Most other systems cover larger delivery areas. My complete amateur comment is that you need different algorithms for different countries.

I frequently have to deliver the bad news to bewildered drivers that the federal building they are looking for is in the middle of Seattle, not on a suburban street Kirkland which just happens to have some similar street numbers - they are always using Google maps directions...

Or MapQuest, who have the best commercial licensing terms I've seen (which isn't saying much), and who also have a passable API.