There are many kinds of application servers, ranging from free and open source products to very expensive commercial products. Today, some high-quality commercial products are also available as open source products, which means that they are free to use if you don’t need professional support by the manufacturer. However, most of the time, the choice of the application server is not made by a developer. The choice is often not only based on technical arguments; most of the time, costs and company policies (such as preferred suppliers) do have their influence on such a choice. For that reason, we are not going to spend many pages on different application servers here. We will just focus on the configuration steps that have to be made for virtually every application server when it comes to using Apache MyFaces.
You should realize that any Java EE-compliant application server bundles a JSF implementation, because JSF is a part of the Java EE standard...