CPA for me by far. I make only a couple dollars in adsense, compared to a few hundred in CPA offers. Depends on your site and what your doing tho
The question doesn't have a simple answer. It depends. There are advantages and disadvantages to each. For example, with Adsense, Google prohibits you from asking or encouraging your visitors to click ads. However, with CPA programs, the way to be most successful is pre-selling your affiliate products or services -- recommending the products and encouraging your visitors to buy them. Many people make the mistake of treating CPA programs like they would Adsense, by simply throwing up a number of banners and hoping that someone will click them and buy something.
I would say they are pretty close, but I use adsense more and so do alot of webmasters. I guess Adsense is just more popular.