You might find it useful to read this blog entry on Choosing a Data Persistence Strategy:
http://www.codefutures.com/weblog/andygrove/archives/2005/01/choosing_a_java.html You did not say whether you just wished to find something for future projects or if you also need to retrofit the solution back into existing applications. That could have a big impact on your technology choice.
Also, you did not say if you have used DAOs in your existing architecture, which will make changing your persistence technology choice much easier.