I recommend ConvertKit over MailChimp because of its active tagging features for dynamic segmentation of your email list. I used MailChimp for years but switched when they dropped many features from the free plan. I then went to ConvertKit and now use ActiveCampaign because of its customer relations management system.
ConvertKit is a full-featured email service provider (ESP). Thanks to its ease of use, automation, and other features, it’s one of the fastest-growing email marketing companies around. It also offers customizable sign-up forms and landing pages to help bring in more email subscribers.
Mailchimp is a marketing automation platform designed and developed for businesses using email to reach out to their target markets. It is an all-in-one tool where you can manage your mailing lists, create custom email templates, and nurture and automate your entire marketing campaigns.