MSN and Yahoo have different demographics of users then Google does so it's hard to say one is better then the other, they are just different.

Google does have many more people using it then the others though, so depending on what you are trying to accomplish, it is going to be beneficial to rank well there.

Unless they make some serious negative changes Google is going to be the top player for quite a while. No other search engine is used as a verb.

When the daughter of one of the Yahoo founders was thrown out of a night club she yelled at the bouncer "Do you know who I am? Google me b****!"