Sure I can recommend a reporting tool, but it will ultimately depend upon your requirements and budget.
Do you need to roll out reports into your organization, or is there one lone analyst that does all the reporting through Excel?
A VERY cheap solution is combining reporting views (in the database) within DB2 and using either Access or Excel (with Microsoft query) as a front-end.
If you want to distribute and manage your reports and allow end-users a maximum of freedom you may want a real BI-tool. Now, I could list a few, but I will stock with the one I use: Business Objects.
A possible route is to acquire the Magic Quadrant Analysis on BI tools on Gartner to get an overview of the field:
Senior Application Developer BI
SQL, SQL server