If you are simply blasting out a single generic email thank you and monthly newsletter Infusionsoft is absolutely overkill. Infusionsoft is not Hubspot Lite...It's absolutely fantastic if you need a very sophisticated email automation solution, just make sure you have everything in place to leverage it.
For teams of 1-2, BigCommerce will get the job done. It's not a big investment and will allow you to customize one of their themes and offers more functionality than other small shopping carts...If you're somewhere between beginner and intermediate in the eComm world, then it will certainly work as a good stepping stone.
While MIVA is lacking in a mobile friendly option and the ability to easily sell soft goods like mp3's or eBooks, these additions are coming to MIVA soon. The lack of connectivity to popular POS systems is also a negative for us. We will certainly continue to offer MIVA Merchant to clients.
Well suited if you are wanting to implement a solution with minimal staff or resources to support a large project such as E-Commerce software delivery.
If price isn't an issue, and you need a lot of reporting tools, Bronto Marketing Platform is a great system.
Demandware has allowed our agency to build a great SEO foundation for many of our fashion clients that previously struggled with their old CMSes.
Adobe Business Catalyst is our go-to web CMS and, until something comes along that is a lot better, we're going to continue using it to develop our lead-generating websites.