I couldn't be happier with SendinBlue. In my case i'm using it for my transactions e-mails for my e-learning site and they work like a charm. I also love the detailed reports, so i can see that my students are actually opening the e-mails from the orders.

And they also have integration with Wordpress and Woocommerce. They also have automations lie abandoned cart and so on. An established and mature e-mail solution, that will fit well for any user case.