I've driven an
E39 M5 and I have also driven an
E60 M5. My conclusion is that they are both great cars, but I feel like I would pick the E39 absence a 100 hp power difference.
The biggest positive about the E39, is that the torque hits you at a low RPM where as in the E60 you have to wait for the higher revs to kick in before you feel it.
What are your thoughts?