Personally I like Google. I think very highly of them and with all the corruption that goes on in the world, I trust Google. I form this opinion because Google has never given me any reason to think otherwise.

Yahoo on the other hand, a grand organization I don't trust as much. I know that their goal is more registered users. The more they have, the more they can brag about and the more money they make. Even though Yahoo's overall goal of getting more users isn't perfect, the services they offer in reach of that goal is very helpful, so no big complains.

Google's mission, ("To Organize the Worlds Information") is beautiful and their recent move to provide service to China is very controversial. I am totally with them on this. I don't agree with China's government but if you look at the big picture, you'll see that a limited version of Google's service will help the Chinese people more than if there was no Google service at all.

Read what Google has to say about all this:
http://googleblog.blogspot.com/2006/01/google-in-china.html