What are you using for binding XML to Java? JAXB, Castor, and XMLBeans are some of the available choices. The comparisons that I've seen are all three or four years old. I'm open to other suggestions. Marshalling / unmarshalling performance and ease of use are of particular interest.
Clarification: I'd like to see not just what framework you use, but your reasoning for using one over the others.
JiBX. Previously I used Castor XML, but JiBX proved to be significantly better, particularly in terms of performance (a straight port of some application code from Castor XML to JiBX made it 9x faster). I also found the mapping format for JiBX to be more elegant than Castor's.
JiBX achieves its performance by using post-compilation bytecode manipulation rather than the reflection approach adopted by Castor. This has the advantage that it places fewer demands on the way that you write your mapped classes. There is no need for getters, setters and no-arg constructors just to satisfy the tools. Most of the time you can write the class without considering mapping issues and then map it without modifications.