This is funny. The only difference that makes the difficulty gap between a monk and a dragoon in our main rotation is that monks need to worry about greased lightning upkeep and has to more frequently worry about their position to maximize DPS; in exchange, dragoons worry about the right time to use their off-GCD skills (jump) which can be fatal if used wrongly, and their 2 positional skills are extremely important for their DPS (1 gives the main buff for dragoons, the other is the combo starter for the 2 main debuffs, use them when not in position and they do nothing).
Ultimately, id say its harder to play a monk, because greased lightning buff has a rather short duration, and having to worry about your position more frequently is harder to manage.
But to put any of the ranged classes in front of a dragoon's difficulty is just... too troll to comment on.