Tanking is almost certainly the easiest in most games that I've played. DPS can be trickier, because if you flub stuff, it can cost you considerably getting back to your proper rotation. In my own experience, healing is also generally quite easy, so long as people are doing what they're supposed to do - not that they ever do xD
"To be, or not to be - there is no such question. To be! But to be what...?"
FFBE friend ID - 432.640.287 - nekrodev