ECS is simple to get started, but does not have a vast array of features that are necessary to run a service reliably at scale. It is possible to add many of these to ECS, but it’s left as an exercise to the reader to write up various API’s, cloudwatch, Lambda, etc.
I can provide more specific details if there’s questions.
I've recently moved from ECS to Kubernetes, and much prefer kubernetes
In general ECS is fine when you have 1 or 2 services, but once you have 10s or 100s it gets pretty unusable.
Logging: While ECS ships everything to cloudwatch, actually accessing them is a nightmare and usually more effort than it's worth. It's very easy on k8s to get logs shipped from every container to elasticsearch and browse with kibana.
Autoscaling: Possibly less of an issue now that fargate's a thing - but fargate's expensive. Kubernetes makes it easy to set up both node level autoscaling, and deployment level autoscaling
Ingress: With ECS you have to set up loadbalancers for every service individually - in k8s once the controller's properly set up every service defines its own ingress, and the only manual change you have to do is create a DNS entry (only if you can't use a wildcard)
Metrics: Prometheus is very ingrained in kubernetes, and you get a wealth of information from every service almost "for free" once you've installed it.
And more: service meshes, secret control (through e.g. vault), declarative definitions, provider agnostic
Kubernetes has a huge startup cost and learning curve, but is incredibly powerful once you're up and running
Autoscaling: No need for Fargate. Create 'AWS::ApplicationAutoScaling::ScalableTarget' and 'AWS::ApplicationAutoScaling::ScalingPolicy' for your 'AWS::ECS::Service' resource.
Logging: Subscribe the ElasticSearch Lambda to CloudWatch Logs group to have all logs in ElasticSearch domain. Kibana is included in 'AWS::Elasticsearch::Domain' resource.
Ingress: Yes, one ALB per one autoscaled ECS Service, I don't see it as a problem.
Metrics, And more: not sure I see the benefits. CloudWatch has miriad of metrics, you can get lost there :)
I can provide more specific details if there’s questions.