Do you use an email marketing platform?

I'm working on a school project and we are trying to improve the experience of an email marketing platform. In your opinion, which is the best email marketing platform and what makes it great? Also, are there any things you'd like to improve about the platform?
It'd also be helpful if you could complete a survey. It will only take a few minutes!

Survey: https://docs.google.com/forms/d/e/1FAIpQLSehV2oHA8J-14IEOaI5bk35cJyonO6dB6s2n7LN3NFwjf3jUg/viewform