I just switched over to a new autoresponder that I am trying out called AutoResponse Plus. I like the fact that you pay a one time fee and save money over time. With aweber, you pay a monthly fee. With AutoResponse Plus, they install it using your cpanel for free. You have complete control over the autoresponder where as with aweber, there are strict rules to follow. You might check it out here:
AutoResponse Plus - Profit Building Autoresponder Software
Onwards and Upwards,
Kit