the problem with paypal's solution is that you either require your customer to create a paypal account which is a hassle and looks a bit unprofessional, or you store the credit card information yourself to do recurring billing. if you store credit cards yourself, in order to be PCI compliant you have to store them on a separate machine on a separate network from your web servers. if you're starting out small, that can be a big pain. paypal does offer recurring billing to an extent but you don't have much control over the process.

braintree offers "securevault" which lets you store the credit card info at their site and they return you a token for each customer. when you need to do recurring billing, you just submit the request to their server and pass a token instead of a credit card number and they take care of the rest.