For those using CQRS / ES in a .Net Core environment, what Event Store are you using? I have had some good success with Azure Cosmos DB (formerly DocumentDB), with Redis Pub/Sub + Observables for handling generated events to create projections etc (also RabbitMQ).
But looking at some of the alternatives for managing event streams, such as Kafka, makes me interested in hearing other opinions as to what could be worth exploring in the JVM world, which has mature solutions, with particular focus on event streaming / scalable event stores.