Email Automation + Transactional Email stack for SaaS?

Keen to hear what other SaaS marketers here are using... We're still using Mailchimp and transactional email (previously Mandrill) but noticing more and more limitations over time. Cart abandonment templates only work with ecommerce integrations as an example. Drip seems to be ecommerce focused, Convertkit for creators - what's best for SaaS? ActiveCampaign looks interesting, has anyone used it?