Well it all depends upon your specialization, i am marketing on pinterest...
And as everyone knows that mostly pinterest traffic comprises of girls
So girls + recipes (clickbank product) = $$$
You just have to strictly study your traffic and your target, try different products...
Like i tried more than 20 products and got sales from only 2 products, which were from recipes
So just start testing, don't just sit around,
Test different products, see how many of them reach payment form and how many convert then select related products and take it to next level