Paypal is still at number one.. But other services like MB, Alertpay are also good..

I must say that Paypal is the best of them all in my opinion. Have never had any bad experiences with them, easy to use, and most people use it. Perfect. Now if you want more security then go with escrow

CHARGE Anywhere has a payment gateway with online services. They are reasonably priced and have been breach free for as long as they have been in business. They offer shopping carts, payment forms, and bill presentment.