RFC - Java/SQL Server Reporting tools

Hello, I'm looking for [Subject/Title]

Must be free/open-source. I need to extract data from a MS SQL Server database and design typical reports containing summations, groups, etc. Later it will probably be an Oracle database that supplies the values.

Can anybody recommend (or, just as importantly, "un"recommend) any of the following:

Jasper?
JFreeReport?
FreeReportBuilder?
OpenReports?
Openl?

Or... ???

Jasper is one of the more common reporting tools out there. It has a huge community and resources to back it up. Have not used the others. but I'd bet functionality wise they are similar (although perhaps without the community and resources - again I don't know and you should research each with these points in mind)