None of the API's involve actually storing the data locally. AIM, CIM, and ARB do involve credit card data being passed through your site, so if you don't want to get into that, you're left with DPM, SIM, and hosted CIM. You don't need hosted CIM for single payments, so it's pretty much a choice between DPM and SIM, with DPM giving you more control over the look and having the payment form display on your site (though it submits to Authorize.net and no credit card data passes through your site), and SIM requiring less work to implement and no SSL (technically, DPM doesn't require SSL either, but nobody's going to fill out credit card information on an http:// URL).
