I would like to add pricing factor too,

ECS is not billed, we pay for Fargate service CPU and memory used, And if its EC2 cluster we pay for EC2 machines.

In EKS, we are charged for Cluster since they manage control plane. I believe its nearly 72$ per month. We are also billed for Fargate or EC2 we use.

So if you plan for less micro service i think it would be good to go with ECS. Also If planning to stop service at unused times it would be better opt for ECS.