Fantasy pros: less expensive per night, more nights, better adult areas, better promenade deck, two adult restaurants, two hot tubs for regular guests with no upcharge, Midship Detective Agency, mini-golf, better windows in oceanview staterooms and virtual portholes in inside staterooms, fewer concierge guests (so less ship space taken up by concierge, and fewer activities/amenities out of reach because concierge has already booked them up)
Fantasy cons: vibration issues in aft staterooms