I switched to ActiveCampaign, from MailChimp, about 18 months ago, and I'm absolutely thrilled with the switch. AC has an incredible drag-and-drop interface for building automations. I can do just about anything I want with my automations, and I can see, visually, how it actually works. With MailChimp, I felt very restricted by their limited automation builder, plus, there wasn't a visual interface for it. Every ESP has it's pros and cons, though. I'd say AC's is that 1) Their email builder is terrible 2) Their site is incredibly slow, especially when doing search queries, and 3) I had some deliverability issues early on, so watch closely, and contact support if you have an issue. I wrote about my whole thought process behind the switch here: http://kadavy.net/blog/posts/mai...