well, I was under the assumption that most batfish were not reef compatable and have been known to pick at corals. As for the decorator crab, do you mean the arrow decorator crab or the spider decorator crab? Either way, they both supposedly will rip apart pieces of soft coral to 'decorate' its shell with in an attempt to camaflouge itself.
As for the others listed, I think they are all pretty much known to be coral safe. Clowns will sometimes move corals around if they are in the way of their dwelling. If I had to place a bet, I would say either the batfish or the decorator crab. And yeah, I'd probably lean towards the crab first.