Via acquisitions and internal product developments over the last year+, Splunk provides really differentiated APM and monitoring for microservices and AWS. I'd recommend giving it a peak if you haven't yet! For some validation, a recent Cloud Observability vendor report by GigaOm came out and ranked Splunk as the "top performer" in the space. Hope this helps in your search
Maurice - Datadog allows you to monitor microservices by unifying metrics, traces, and logs all in one place. Enabling you to visualize how services interact at a glance so you can quickly locate problems and begin troubleshooting. On top of that you can monitor complex dependencies, investigate possible points of failure, and set smart alerts for proactive monitoring. In my opinion Datadog offers the most comprehensive tool with the simplest UI.