It depends on your strategy. Amazon affiliate blogs are high volume, smaller profit margin with sites going after multiple products. If you target properly, the sales are generally easier to make. With ClickBank, you'll only be selling one product, but the margin is usually much higher. So you can sell, for example, 100 items with a $3 profit or 6 items with a $50 profit. If you're doing, say, a blog on widget building, you can Amazon affiliate all the tools and materials required for widget building, even Amazon books to help build widgets. You can also just sell a great course with 1000 different widget plans from Clickbank. Either way, with enough elbow grease, both are viable choices. It all boils down to which is better for you individually.