I have with both. Datadog is about as plug and play as you can get. I did a few days of work with Elastic cloud. My takeaway was:
• If you can’t afford datadog then elastic cloud is pretty cool.
• If you can’t afford datadog but spend big money on other stuff, maybe question your priorities and engineering time involved?
• If you are already super versed in Kibana/Elastic stuff, then you might have a great time. My stack has been more prometheus, influxdb, grafana, etc. I found the Elastic managed saas service very different and complex for my needs.
• Elastic was a lot more engineering effort for the same level of integrations that I observed.
My 10 cents!