These are the best comparisons I have found. It is a hard task to compare frameworks and almost impossible to be neutral.
- A Comparison Model for Agile Web Frameworks – It is really an old scientific article: 2008. But it is the most neutral comparison I have found. It is interesting to see how it is done.
- Categorization and Comparison of Popular Web Frameworks in the Java / JVM Environment – It shows a clear map of the types of web applications you can find and which frameworks you could use. Of course, some frameworks are missing.
- Comparing JVM Frameworks – It is not neutral, it is Raible’s view as he says. But his speech is a good introduction to comparisons. Furthermore, he uses a matrix based on framework attributes and grades given to these attributes which is useful to be modified personally.