That's the question. What are the options do they have for the publishers? And what are the payment methods available?
CJ - no payment through Paypal check and Direct Debit only. CJ - mainly deals in real world tangible goods, so publishers / merchants usually offer a % or fixed price per sale.
Commission Juntion no payment though Paypal, just only check and direct debit. Check is the best available payment method with CJ.