All three of them offer Free account. Campaign Monitor allows you to browse through the basic features but as soon as you are ready to send your first email, it will ask you to upgrade.
Mailchimp didn’t have that limitation but the setup and configuration process was too much verbose to my liking. The subscriber form and the email templates weren’t very good looking either.
Sendicate on the other hand had fewer features but the implementation process is very direct and intuitive. The free plan allows you to have send email to 1000 subscribers/month which is more than enough for me at this stage.
I am hosting the subscriber form on my website and you can subscribe by simply entering your email address in the form on your left. Sendicate offer predefined templates with the ability to schedule emails to be sent on a weekly basis.
However, the email will only be sent when the RSS feed has new content. The entire process took me less than 15 mins to setup. Make sure you subscribe and stay updated with all the latest content on my blog.