I have two: Peace and Crystal. However, Crystal offers NO customization. It's all or nothing deal with no exceptions. If some site stops working because of it you have to go to the settings and disable Crystal. too annoying. Peace is great and does offer some customization including the ability to turn it off on a site directly from safari. However, Marco Arment, its developer, had some ethical issues with his own app and pulled it from the App store.
There are plenty of other options for adblockers though but I have no first hand experience with any of them