It seems to me like there are four main options when it comes to online mapping:
1) Mapquest
2) Google Maps
3) Live Search Maps (formerly Windows Live Local) aka Virtual Earth
4) Yahoo! Maps
First of all, I think that mapquest is outdated, and I don’t see Yahoo! maps as having anything special over Google or Live Search. So that leaves me with options 2 and 3. Google Maps is nice in the fact that it is fast, and you have really good satellite coverage around the world. In addition, there are street side imagery which is quite cool (but also a privacy issue). Live Search Maps has good satellite coverage in the US but some countries it is really lacking. However, Live Search Maps also has Bird’s Eye Imagery which is imagery from a plane that they took as they flew over an area. You can also see buildings in 3D, and the quality is much better than Google Maps in that regard (They actually designed a specific camera for the job!) Live Search Maps does not have street side imagery yet, but if you go to preview.local.live.com you will see that they are working on it (that webpage has been there since before street side imagery by Google I believe..)
So I would say in this round that the vote goes to Live Search Maps. What do you think is the superior mapping service?