I used Experiture for just over a year and they were so-so, not slick and sexy like some other UIs. They're also not as cheap as some of the big guys like Constant Contact or SendGrid. Deliverability became an issue for us so we had to find a new service.
eTrigue - Real-time Sales Acceleration & Marketing Automation Solution
Pardot - Salesforce B2B marketing automation
WiX - Create a free website with Wix.com. Customize with Wix' website builder, no coding skills needed. Choose a design, begin customizing and be online today
Campaign Monitor - Email marketing software built for designers and their clients to run successful email campaigns.
MailChimp - MailChimp is the best way to design, send, and share email newsletters.
SendX.io - SendX (https://sendx.io) provides remarketing and retargeting tools for web businesses. You can use popups, landing pages, email, web push notification, automation workflows and FB / Google retargeting to drive more revenue.