The choice between Apache Spark, Akka, or Kafka is heavily bent towards the use case (in particular the context and background of the services to be designed) in which they are being deployed. Some of the factors include Latency, Volume, 3rd party integrations, and the nature of the processing required (like batch or streaming, etc.).
I found this resource to be of particular help - https://conferences.oreilly.com/strata/strata-ca-2016/public/schedule/detail/47251
