Depends on who you're billing for, as well as the type of solution you're looking for. Do you want an integrated Clearinghouse? (I think it's a good idea) Do you want your customer to have access to a Practice Management or EHR? Obviously, a cloud / web based software would be beneficial as you can use it anywhere, at any time. With cloud / web based software comes month-to-month costs, so you'd want to find an affordable solution.