I did try Earth Shock in my rotations due to the enhanced range, but found that it didn't do enough extra damage for the 1.5 second cast time to be worth it.
If I recall off the top of my head:
Earth Shock: 1.5 seconds for about 1300 damage (yes, it is an instant, but the global cooldown makes it act like a 1.5 second cast time)
Lightning Bolt: 1.75 seconds for 1550 damage
