Have you used online rent payment, as a renter or landlord?

A client with a few rental apartments is interested in electronic payments.

Do you have any advice, or tips? Any steps a landlord should not miss. Any missteps to avoid? Any particular service which you like or dislike?

Services we have considered are PayYourRent.com, ClearNow.com and RentPayment.com. We have no preference among them and are open to suggestions.

TIA!