Social Networks like Facebook will always have their haters and lovers, but email will be here to stay for the long haul. It's the true neutral medium of the internet.
Anyone who has used the incumbent tools knows they don't work as well as they advertise. ConstantContact is a behemoth that fails to innovate. MailChimp has a cute monkey but the product is less than compelling. Kudos to Sendicate for creating something unique, because this is a space that needs to be taken to the next level.
Sendicate is interesting because of it's opinionated approach and great modern design.
If you already have a design though you should try Mailrox (https://www.mailrox.com). It's dead easy to upload designs and create email templates which can then be used in Mailchimp, Campaign monitor or other services.