I find, out of all the places I've ever used, that ClickBank's refund policy is the one that suits me best, as an affiliate. It's their refund policy that makes it so easy to sell the products. And it's one's own marketing skills as an affiliate that determine whether or not one's customers do actually refund. Some affiliates have refund-rates well under 1%, and some well under 0.5%, for all the products they promote while other affiliates have refund rates well over 10% for those same products.
One of the cool things about Google AdSense is that it's so easy to get set up. If you have a blog or website, you can sign up for a free Google AdSense Account. From there, Google will give you a unique code that you will paste onto your website. Google takes it from there, tracking your page views, traffic, and earnings on your behalf. There is no upkeep or maintenance to get this thing going, which makes it a no-brainer if you have a website already.