NIN/MNK difficulty?

[Shamox]

Uh, how does this differ from literally every other job in the game? I have to adjust my opener on Samurai for better optimization on V3S based on Spellblade Holy, for example. Dragoon moves its buffs around to properly align with the raid for "burst phases." Mapping out Trick Attack isn't any different than maintaining Greased Lighting or BotD throughout phase skips. In fact, both of those can be far more cumbersome on specific fights. You seem to be creating this illusion only Ninja has to optimize their rotation based on a fight. Ask a good Black Mage or Summoner the sheer amount of micromanagement that goes into their opener and Ninja's isn't even close.

To answer the OP's question. I would rank Monk ahead of Ninja nowadays in terms of overall difficulty. For the melee in general: Dragoon >= Monk > Ninja > Samurai would be my rankings.

This was a NIN - MNK comparison.
While most melee rotations are rigid (DRG being the best exemple), NIN (and kinda SAM) offers you to switch combos order at will. Ninki mapping is also a very different thing than just "switching buffs" around.
Comparing TAs mapping to maintaining GL and BotD during phase skips/disengaging situations > ?

I only rejected the fact that monk would be harder than NIN, every melees are pretty easy to pick up and once you can play one decently you probably can play all 4 of them.