Among the three options, I have only used Mailchimp before.
It has a set of robust features as compared to other providers in the market and they are constantly adding new ones. For starters, they also offer a free plan. However, if you are planning to promote money making schemes, business opportunities or affiliate marketing offers, then Mailchimp may not be the right solution because they specifically pointed out that sending out emails promoting these offers is a violation of their terms of service.
Personally, I am using AWeber.com because I build several lists on the same website. I need a service that automatically recognizes the same email address from two different lists, and only broadcast to the email address once instead of twice if I am sending to both the lists. Last I checked, this wasn't possible with Mailchimp.