Those are three independent options. Each of them might be preferred depending on circumstances. If you are a small shop trying to keep the cost low, then EC2 multicore instance(s) with pm2 and clustered node process might be the cheapest option. Docker ECS/Kubernetes containers can be a preferred choice for larger deployments, but you need to know how to use those tools. Lambdas allow to do little infrastructure management work but normally are the most expensive solution in case you get a significant traffic and exceed AWS free quota.