My experience of ECS is the opposite of yours. It integrates nicely with the AWS ecosystem and was substantially easier to use and educate others on. Would not hesitate to use again on either fargate or BYO EC2. I will acknowledge scheduling is not quite as fast as Nomad but I never found it 'slow'

Personally, I'd rather create a k8s deployment than an ECS task, but I can see your point. If all you want is an integrated with AWS experience, then it makes som sense that ECS is just simpler overall out of the box.

I don't think the delta to make k8s integrated is that much work with EKS, but ability to mutate the entire infrastructe if and when you do scale wins out for me. I think the complexity, most of which you can ignore, is worth the flexibility.

Either way, since k8s landed, AWS itself has started improving too.

I've used both and I would still prefer ecs/fargate to build a rather independent application and k8s to build a long-term platform.