Adsense is far better because it has much audience along with availability in most parts of the world
Of course Yahoo Publisher is better, but its not easy to get an account from them.... since its still beta now
Google is the best and not only than yahoo but all other networks because Google have high number of advertisers and in turn it gives high rate to its publishers.
google adsense is very easy to join (if your page are not warez or adult), but they started to pay cents Most of my click's is 0.01-0.02$
Google is the King, they are bunch of smartest people making rational and good decisions. Adsense is like the inventor of ads on the internet. Without it Internet does not have life.
It's so funny to see how many responses here are just mentioning that Google is the best, it's clearly so true! Google has run with AdSense since they first let it out a few years ago, and recently Microsoft's PubCenter has been the latest competitor with them.