Healing as an esper is fun, this I can tell you, you can be fully mobile and stop casting only Mind over Body which has its uses, but it's certainly not a skill you spam. Soothe is the go-to heal and is very fun to use imo. I never had focus issues, even with low dps groups, but I'm not 50 yet, so I won't comment on top level content.
Let's say that out of the 3, esper is certainly the healer I like more, by a long shot.
Medic was also kinda appealing, but you need a group that doesn't scatter all over the world, so quite coordinated, while esper tends to be more friendly and forgiving with positioning (not too much).