An affiliate marketing program is a lot of work, and in most situations there's a lot of competition so you're not going to be bringing in money immediately. Business owners and entrepreneurs suppose that all you need do is setup a site and choose an affiliate to associate with and then just let it run its course. But according to Three Ladders Marketing, only 0.6% of affiliate marketers surveyed have been in the game since 2013. That means that affiliate marketing takes time and effort to build and make money.
I know it’s part of Shareasale, but Wayfair might be worth mentioning. They’re a huge site (mainly home & garden and pets) and actually have a better selection than Amazon in a lot of categories. I used them successfully on an old home furnishings site I had since Amazon’s selection of products was lacking in this particular niche. 5% commission on everything with a 30-day cookie and easy to get approved from what I remember.
Look for a gravity score of 30 or more, because these products have a proven track record of selling well for a number of different affiliates. Products, especially new products, with gravity scores under 30 may work but are more risky. Gravity scores of greater than 100 mean the product’s popular. You could have competition, but don’t worry about that. The important thing is that there’s lots of demand.
From what I’ve observed, most of the “programs” you’ve listed are networks, and most of them support dozens, hundreds, even thousands of merchants – in a huge variety of niches. Amazon is not technically a network, unless you factor in the presence of about a dozen entities like Zappos, Woot, Endless and the like. With very few exceptions, networks are diversified. Performance-Based.com focuses on eco and green merchants. Some support a particular locale – European merchants, for example.
The concept of affiliate marketing on the Internet was conceived of, put into practice and patented by William J. Tobin, the founder of PC Flowers & Gifts. Launched on the Prodigy Network in 1989, PC Flowers & Gifts remained on the service until 1996. By 1993, PC Flowers & Gifts generated sales in excess of $6 million per year on the Prodigy service. In 1998, PC Flowers and Gifts developed the business model of paying a commission on sales to the Prodigy Network.