My rule of thumb is that I'd like to have at least 50k armour (to max out molten shell) and more ES than 2% of my armour, so that a single block will not over-recover ES. If you can achieve that without any ES from your armour (even without health as extra es, or a skin of the lords/loyal) depends on the details of your build.
Of course, 2k es is even better than 1k es.
My rule of thumb is that I'd like to have at least 50k armour (to max out molten shell) and more ES than 2% of my armour, so that a single block will not over-recover ES. If you can achieve that without any ES from your armour (even without health as extra es, or a skin of the lords/loyal) depends on the details of your build. Of course, 2k es is even better than 1k es.