i dont think you can compare a CPA network with PPC network - both are good in their respective niches
There are pros and cons of both but they cannot be compared. It depends on what you want to do with both companies. You can include both on your website or blog to make money with both.
It is difficult to compare two completely different companies. Adsense is good in some ways, and Clickbank in other ways.
You really can't compare the two but pros and cons? Well adsense, from the moment you have an active account you will always be standing on thin ice. It's so easy to get your account banned.
Adsense is a CPC Network and Clickbank is a CPA Netowork. It's not possible to compare them, but Adsense always works better than Cickbank in my sites.
Adsense pays less but you get paid per click. Clickbank pays more but you get paid per sale, which requires more effort. Which you should use will largely depend on your traffic. You need very targeted traffic to make sales with CB.