in my opinion sumrria.com is the best affiliate program. Sumrria pays it's members to do simple offers and view ads. You can also use your accumulated earnings to purchase ads or cash out. Earn even more whenever your referrals purchase ads or even view ads.
Loved the fact that EngageBay is right there on the list. It has to be one of the most consistent and rewarding affiliate programs in the SaaS/CRM niche. Cheers!