Considering that any NQ token can be handed in for the 3 bought items and the hard-to-find item in the recipe, I'd have to say that any 4 star item is harder to get.

Lucis is only time consuming, due to the sheer number of Moonstones and "Duck Bone" (and similar items for the other crafts) and the need to craft 20 tokens. That's not difficulty, that's tedium.