I have done everything from deploying to Tomcat servers to modern k8s. I really don't like Cloudformation and ECS, arcane and poorly documented syntax. I like much more having a Helm chart for my apps. Have you ever tried to set up private DNS in ECS for services to talk? That doesn't look simple (or well documented) at all to me.

By the way, Terraform and k8s are not exclusive, I use them together.