What are the best Kafka as a Service Tools?

Confluent, Amazon Managed Streaming for Kafka, Apache Kafka on Heroku, CloudKarafka, and Aiven for Apache Kafka are the most popular tools in the category "Kafka as a Service". "Free for casual use" is the primary reason developers pick Confluent over its competitors, while "No" is the reason why Amazon Managed Streaming for Kafka was chosen.