Well its not about best affiliate program ,its about your skills as affiliate marketar and ability to drive traffic .Firstly you need to think of a topic where you like and you have a passion ,it can be make money online ,relationship ,spurituality ,weight loss etc .Then you need to choose an affiliate offer by joining clickbank as an example or go to google and type your niche + affiliate offer and google it will show you a list with offer in your niche .Then start creating yoyr platforms like youtube ,blog ,social media ,forums ,fb groups etc .In here you create content ,help people by answering questions etc and from time to time you recommend your affiliate offer