Among adsense, bidvertiser and adbrite, which is the best?

The best depends on your area of expertise, how 'niche of an area you're actually planning on posting blogs or making websites in, and how well your site/blog fits the guidelines if the given "revenue-provider"

With that being said, Google Adsense is generally the strictest but pays the best. If you don't break any of their rules & follow the rules they do have to a tee you'll earn quite fast. Their guidelines are VERY strict though & if you break just one.. or you're SLIGHTLY off there is a chance you'll be banned permenently from their Google Adsense features.

Bidvertiser is about the 2nd most popular one and has a fair share of money to be earned if you're in the right area for blogging/making your website in. Although you won't earn nearly as much as you would being on Google Adsense, they have looser guidelines which means more potential to earn from not just Bidvertiser, but other sites that profit you such as PayPerPost.com.

Adbrite is decent but well. It's lacking in the amount of revenue you can make. It's a good site if you hit their VERY niche' areas, though considering not many people use it and the people that do in the areas they're looking for.. is generally higher in demand then you would find in the other two you mentioned. But even being in higher demand for some of the advertisers(Meaning they'll be willing to pay more) still might not add up, and you still might be taking just as long. Not an advised method of earning.

For most people, Bidvertiser seems to be the best bet. It's actually the most profitable & stable if you accompany it with other methods of earning such as the one mentioned, payperpost, as well as others like sponseredreviews, and etc. You might want to check each and every site that you look into for earning carefully, though. If you miss something in the TOS/Guidelines you may have just wasted your time and be banned on the given site or your site/blog not accepted at all by whichever you consider.