What software do you use for email marketing automation?

For the last month, I'm struggling to find a good SaaS solution to set up my automated email campaigns.

The tool should provide:

• Automation workflows with A/B tests support;
• UI editor to create templates;
• REST API to subscribe contacts and trigger events that can be used in automation workflows;
• Reports with all the regular email metrics (like open rates, unsubscribes, and such) per each email in the automation;
• Reports for A/B tests.

Sounds simple, but after exploring the market I found only two solutions that fit my criteria: Sendinblue and ActiveCampaign.

I opted in for Sendinblue because of the cheaper prices and now am regretting it. =(

It turned out they have hidden costs and limited functionalities on the reporting side. On top of that their service went down a week ago and since then I've managed to send 0 emails. Their customer support is playing ping-pong with my tickets already for a week without any prospects of resolving the issue.

I'm wondering if any of you have a similar business case and how did you solve it? I'm doubting between migration to pricy ActiveCampaign and developing my own bicycle on top of AWS SES.