Mailchimp is the best, is the most used and the one that has better support and tutorials.
Anything else is to mess up and more at the amateur level. Take a standard, learn how to use it through your training or millions of tutorials on youtube and when you see your exact and real needs then you will be able to find something tighter (if there was one).
In addition mailchimp leaves you free until the next thousand users, which is not bad.
Also, for what we are going to deceive, probably after going through mailrelay and things like this you will finish in mailchimp.
In particular i would suggest you to try Aweber, since it offers rich e-mail creation and modification, and a bevy of templates ready to be customized to meet exacting needs.
The bottom line is that the average follow-up autoresponder is no longer sufficient in a day when customers demand quality e-mails if they are going to convert.