Which boat trips are actually worth doing and which are the same trip sold three ways?

Every shop on the beach road is selling what looks like an identical day out to the same islands, at prices that vary more than the itineraries do. I assume some of them are just reselling the same boat. What I’d like to know is whether any operator genuinely does it differently, smaller groups or a better route, or whether it really is one trip with different stickers on it.