With your criteria, I feel like either ship would be a good fit. I'm wondering what additional preferences you might have that would "make" or "break" your vacation/experience (i.e. noise levels, amount of children present, availability of adult only activities or areas, nightlife, cost, etc..). Without a better picture of who you are as a cruiser, I don't know that this forum will be of much help.
Without any of that, I'd personally go with whichever ship had the newest retrofit and most options- which would probably be the Dream. But again, with your limited criteria, either would probably do.