I would go for Eibach's, as they have a diesel specific pro kit (30/35 mm drop).
But you need to be careful with the standard shocks. They will go in a few miles with the lower springs.
The ideal situation is to change shocks and springs (coilovers maybe?) so that they match each other.
If you change the shocks, be careful with the auto leveling xenon sensors in the back shocks. You need to transfer them to the new shocks, and they usually don't come with any way of attaching them.