It depends on what you're looking for.
If your goal is a low-stress, comfortable, fun, get-away-from-it-all vacation, then I recommend a winter cruise on the Dream or Fantasy, which are DCL's best ships in terms of the amenities they offer to passengers. Their cruises also always include a stop at Castaway Cay, Disney's private island which is the most stress-free port you'll ever visit. Winter is the dry season in the Bahamas, so you're less likely to have your afternoons rained out if you cruise then, and a vacation to somewhere warm is a delightful escape from the dreary winter cold.
If your goal is an exceptional travel experience (in terms of seeing new places), then I recommend a summer sailing to Alaska or Europe on the Wonder or Magic, respectively, as those lovely ships have the best travel-oriented itineraries.