Quote Originally Posted by Darkwing Bahamut
The area in Esthar where you can encounter infinite Elnoyles is a good way to level up as well. Plus it gives you useful items for weapon upgrading.
Yes, but you have to keep exiting and enterting the screen for every one that you want to fight. On the ICH you just have to run around, since the encounter rate is unusually high. Most of the enemies also give you much more EXP than Elnoyles.

The Elnoyle in Esthar is by far the quickest way of getting Energy Crystals and Moon Stones, though.