Earthquake vs Earthshatter?

Torn between these skills, as I'm wanting to do a melee build after getting a little bored of the summoner build I have. But really dont understand the difference between the two? Can someone help me out with pros/cons of the two skills? Which classes would you say work best with the skills?

Most of Earthquake's damage is from the aftershock, so you want as many aftershocks as possible. This means supporting Earthquake with Less Duration Support and possible taking Window of Opportunity to make the slams come out as soon as possible. You also want to time your attacks so you start a new one right after the aftershock. Only one aftershock can be pending at a time, so increasing your attack speed can actually reduce your damage if it causes you to attack before the aftershock has occurred.

Earthshatter is all about the spikes. You'll want to make a plan to detonate them, either with a warcry, Leap Slam, or Tawhoa's Chosen.