It will be difficult to select any server based on the information available on the internet, unless we try it on our own. What is the best way to justify the selection say Glassfish App Server?
For many applications, any server is fine. Two key aspects to consider are scalability and cost. And what the developers/deployers are familiar with.
When I took the cert, I picked one of the servers Oracle owns since it was an Oracle cert. The nice thing is that you aren't actually building/deploying the app you design. So you don't need to use the server!