I can say with pretty solid confidence you won't have a bad time on the other Disney ships. They all are incredible vacations and having gone on the other ships before the Wish, I felt the Wish was not all that different in terms of the baseline experience of good food, phenomenal entertainment, plenty of Disney characters/touches, nice pool/recreation areas and excellent service.
Here are some salient features which may help you choose another ship depending on what you enjoyed most, and will hopefully also illustrate what I mean about a lot of shared features across the fleet (including the Wish).
Main Dining: All four ships have the rotational dining format the Wish does, where you keep your server but rotate restaurants. All four ships have themed dining. All four have an "animator's palate" restaurant with a video screen show conceptually similar to Marvel on the Wish. But only the Magic and Wonder have a live dinner show like Arendelle on the Wish--the Magic has a Rapunzel show, and the wonder has a Tiana show.
Other Dining: All four ships have a "Cabanas" buffet that is similar to the "Marceline Market" on the Wish except they are self-serve buffets rather than cafeteria style, and have a uniform Caribbean theme across the seating area rather than separately themed seating areas. The pool decks on the other ships have pizza/burgers/sandwiches but do not have the Mexican and BBQ quick service that the Wish has, although there is a Shawarma station on the Magic and Wonder. The Dream and Fantasy have a premium ice cream/sweet shop similar to Inside Out on the Wish but the other ships do not.
Rooms: All four ships have spacious rooms with the split bathroom layout in nearly all categories. But the decor is markedly different from the Wish--the theming is classic nautical design with very subtle Disney (e.g., hidden mickeys) unlike the more heavily character themed rooms on the Wish. Still, aside from the artwork the rooms are equally well appointed and comfortable.
Pool deck: All four ships have funnel vision at the family pool area. Dream and Fantasy have the "Aqua Duck" water raft ride which is similar to the "Aqua Mouse" on the Wish but without the portion that has the video screens. Magic and Wonder have water slides, but they are only body slides, not raft slides. All four ships have a larger adult-only pool area than the Wish, but unlike the Wish, no the pools on the other ships do not have "infinity" style views. There are more hot tubs on the other ships than the Wish.
Evening shows: Shows vary by ship, but I found the other ships' shows were the same or better quality--no matter what ship you are on, you've have broadway level performances and impressive costumes, sets and special effects. Dream has Beauty and the Beast, Golden Mickeys and Believe, Fantasy has Aladdin, Frozen and Believe, Magic has Tangled, Twice Charmed and Wishes, and Wonder has Frozen, Golden Mickeys and Dreams.
Other live entertainment: All ships have the sail away party (admittedly, the Wish's is better than the other ships, but the others are still nice), and all sailings to the Bahamas or Caribbean have a Pirate Night (without the live rock band, but with Captain Jack Sparrow and fireworks). Sailings to colder waters (e.g., Alaska, northern europe) have a Frozen party instead of a Pirate party. Plus all four ships have a LOT of character meet and greets. It's all very well done.
Family Activities: All four ships have trivia, bingo, arts and crafts, movie theaters, and family game shows. The Hero zone is unique to the Wish; however, the other ships have an outdoor sports court and mini golf, so I feel like that is a fair trade. Dream and Fantasy have an interactive "Midship Detective" game similar to "Uncharted Adventure," arguably better because you don't need a phone to play.
Spa: The spa treatments are basically the same for the most part, except the Hook's barbery is not on the other ships (though you can still get barber services in the regular salon). If you used the Rainforest Room on the Wish, the Wish has an outdoor space and an ice room that are not on the other ships, but I'd argue the Dream and Fantasy rainforest rooms are actually nicer than the Wish's because their hot tub and sauna have floor to ceiling windows with ocean views.
Kids' clubs: This is one area where I could see being disappointed after the Wish. My kids and I thought the other four ships kids clubs were amazing... until we went on the Wish. The Wish's kid's club takes everything up a level, or two, or ten. But the other ships still have impressively themed spaces, fun activities, and characters. Much better than anything on another cruise line. But admittedly a substantial downgrade compared to the Wish. Just maybe prepare your kids if you have them mentally that it won't have all the same bells and whistles but they'll still have fun.
Itineraries: This is where I think the other ships have a clear advantage on the Wish, because most have longer sailings that visit other ports. Or if you just want Bahamas, consider a "double dip" where the ship stops for two days on Castaway Cay, which is available on certain other ships at certain times of year but not the Wish.
One other difference I hesitate to point out because I personally couldn't care less, but apparently it was a BIG DEAL to some people, is that the other four ships have a wraparound outdoor jogging/walking track on deck 4. So if you like to spend your vacation exercising, ummm, that's a good thing, I guess?
