Originally Posted by
Koros
Here: Cure II is 800 heal potency per GCD and Cure is 500, and Cure II is 0.8 heal potency per MP and Cure I is 1.25.
That means if MP isn't an issue, using Cure II is more optimal since it heals for more per GCD. This is the case most of the time.
The edge cases where Cure I is useful is when MP is an issue, e.g. right after resurrection. If you don't have an instant-cast for whatever reason and just need to top someone off for a raidwide, Cure I is also actually often more useful than Cure II. This happens when you die and lose all your lilies but need to get a DPS topped off before a raidwide so that they survive it. The reason is because they only need a few hundred potencies worth of heal to survive the raidwide, and any extra is wasted (because you have group heals to top everyone off from 1% hp afterwards for example).
When triaging, Cure I can be useful, for example if you just got raised and need to raise your cohealer while making sure the tank doesn't die, and don't have Thin Air for whatever reason. 2400 + 400 MP is plausible but 2400 + 1000 is absolutely not. On other healers, particularly sage and scholar, this is even more important since they don't have Thin Air.