The EntLib Extensions to WSSFhave gotten more and more attention lately. There now is a (very positive) announcement about the extensions on the WSSF site, and there is a complete article on MSDNexplaining how to use the extensions. Check it out!
EntLib Extensions to WSSF: https://www.codeplex.com/EntLibExtensionsWSSF
MSDN article: https://msdn.microsoft.com/en-us/magazine/cc164250.aspx
WSSF site: https://www.codeplex.com/servicefactory