It all comes down to the type of your website and how much traffic you can deliver through your website.
AdSense is the foremost choice in PPC advertising. However, if you are having good volume of quality traffic, you should go for CPM advertising for example, Exponential Ad network. If you have an entertainment/news website, go for native ad networks like Outbrain or Taboola along with CPM ad networks.
I agree with @Messiah, Adsense is the highest paying one.
Also it depends on the country you are based in, English speaking countries paying the highest/click.