Hello,
In my opinion you should use eclipse BPMN2-Modeler as it supports many more BPMN 2.0 functionnalities, however some may not be yet handled by jBPM engine, make some basic processes to test...
I used both of them on few processes and the BPMN2-Modeler is nicer when modeling to my mind.
I think this BPMN2-Modeler will be the one to use in the future under eclipse. Moreover it is mentionned in 5.3.0 user documentation (http://docs.jboss.org/jbpm/v5.3/userguide/ch.eclipse-bpmn-plugin.html => "We are working on a new BPMN 2.0 Eclipse editor").
I posted few days ago a similar question about the available designers maybe you could have a look : https://community.jboss.org/message/751628
HTH