Few things to note when identifying a payment gateway:

1. Setup fees
2. Maintenance fees
3. Transaction fees (especially if you deal high volume)
4. Collection (how soon you get your money released to you)
5. Target market (locals prefer local/direct banking, international don't mind paypal and other CC gateways)

In addition to the above, you also identified another requirement - recurring billing. Meaning at the end of the month, you'd want your customers to make payments for the banner returns they've gained.

Because if they can continue advertising without having to pay, it's a lost for you.