If your developers already have a basic understanding of AWS, the APIs are more similar between ECS and other AWS services. K8s introduces an unrelated API nested inside other Amazon APIs. Imo ECS service setup is a simpler interface/API and the load balancer integration is very good.
K8s can go a lot of different ways depending on the type of LB and whether you opt for ingress and whether your ingress is cloud provided or runs in your cluster.
Same with logging. ECS you just configure a log group and get persistent logging and basic aggregated searching with Cloudwatch Insights. K8s you get ephemeral, unaggregated logs unless you introduce additional tools.
When I worked with ECS, it was originally setup by software engineers and it was scripted using the AWS SDK and worked almost exactly the same as the rest of the stack that used things like S3.
Starting with k8s would require learning a new SDK/API versus some new endpoints in the one you're already working with.
On the other hand, as we grew, we'd hit weird issues like ECS nodes going dead without the backplane rescheduling containers on working hosts (I think they've improved ECS agent health checks since then, though)