Both companies have their own perks. Clickbank will give you higher amount on each sale. It can go upto 75% sometimes. I also started with Clickbank and have great experience with them.
Coming to Amazon, don't get distracted by 4% because there are higher conversions in this network - Trust of people will get you sales. One just needs to send traffic to Amazon, rest the network will do.
Amazon have recently changed their affiliate commission policy, have a look at the new commission structure: https://affiliate-program.amazon.com...rating/compare