Disney is the most expensive (3x) than the next option which is typically going to be Royal Caribbean. While Disney has very nice ships and great experiences for kids that like Disney characters and shows, the ships do not offer Rock Climbing walls, Flow Riders, Go Karts or Sky Diving that you can do on other brands of ships. Personally, I don't find it worth it to go on one Disney cruise when we can go on three cruises with RCL for the same price.

My family prefers the more modern ships (12 years old and newer) on Royal Caribbean because they offer the Rock-Climbing Walls, 2 Flow Riders, Aqua Theater, Ice Skating Rink along with the dry slide and Broadway style shows on-board for a cheaper price than Disney.

Norwegian cruise lines has some solid modern ships that have Go Karts, however, you have to pay extra to ride. I feel like of all the cruise lines, NCL nickel and dimes their customers the most.

Carnival is a cheaper (budget) cruise line and while they have some fun amenities like a roller coaster or pedal coaster on top. They also have really good water parks on top of the ship that the kids will enjoy. The food is typically not quite as good and since its cheaper, you tend to get more of the "riff raff". Just do a google search for "brawl on cruise ship" and you will find many videos of fights on Carnival over the last few years.

Stay away from Princess or Celebrity if you are taking kids.