This article is informative, but it does not offer distinguishing features between the services covered (other than mailchimp is free). You seemed to go to great lengths to say good things about each – although I’m sure each services has positive aspects. I would have benefited much more from a rating of some sort of the various features of each service, or at least the pros & cons of each.
InfusionSoft is a fully functional CRM and marketing solution created for small and medium size businesses. Comparing it to MailChimp or AWeber is like comparing a Lamborghini to a VW Golf. It provides highly advanced features for list segmentation, lead scoring and marketing automation. On top of all that, you can integrate all of these features with your optin form using Infusionsoft Tags + OptinMonster.