Had a chance to work with EclipseLink. If you are using Oracle and don't ahve any plans to migrate to other DBMS or support several DB at one time, you have to choose EclipseLnk, because it's defently better than Hibernate fot your aims.
Awesome things, not available in Hibernate:
1) All queries are generated with Oracle hints - it's can be useful and seems realy cool:)
2) Hierarchy queries are already supported
3) Much less open bugs in EclipseLink project
Also, EclipseLink is etalone JPA implementation.
Also, I love SQL logginig in EclipseLink. It perfect and has binding by default, also it's much more readeble that hibernate log (about logging http://wiki.eclipse.org/EclipseLink/Examples/JPA/Logging#How_To_Configure_Logging)