It really varies more by the specific crew members you get assigned. We've been on the Magic, Wonder and Dream, and our cabin stewards were fantastic on all three. Our serving staff was great on the Magic and Wonder and comparatively lackluster on the Dream. But we saw serving teams around us on the Dream that seemed very good. There's no point in drawing conclusions about a whole ship based on someone else's interaction with 0.1% of the staff.
I have heard for what it's worth that the Dream is the least popular ship to work on, because it just does 3- and 4-day turnarounds all year long, going to
Castaway Cay and Nassau. It's a bit of a grind, I would think. The Magic and Wonder get to go all over, which has got to be nicer for the crew, just in terms of seeing more scenery, getting more varied schedules, etc. And the Fantasy does nothing but 7-day cruises, but alternating East and West Caribbean, so they get a bit more variety. And turnover day is the hardest, longest day for the crew, and the Fantasy has half as many turnovers as the Dream.
But in practice, our Dream cruise was excellent, and the only minor flaw was the servers, who weren't actually bad, just not as fun as our servers on the other two ships. I would take another Dream cruise if that itinerary worked for us without hesitation. But realistically we're not that excited about Nassau, so I don't see another Dream cruise in our future unless they shake up the destinations and send the Dream somewhere more interesting.