After over a dozen cruises on
DCL, my youngest turned 12 and was not thrilled with Edge. Since then, we have taken over a dozen cruises on RCL on a variety of ships. I am going back to DCL with my toddler grandkids for a cruise on the Fantasy in a couple of weeks, and I have taken grandkids on RCL too (in fact we are doing a "S2S" -- one week on the Fantasy and then one week on the RC Oasis of the Seas). I enjoy both lines tremendously. My brief comparison is as follows:
First, with a family on RCL, you need to chose an Oasis-class ship (or the Icon) which are Oasis, Allure, Harmony, Symphony, Wonder or Icon all "of the Seas." Of these, I would probably not pick Allure for teens as it does not have waterslides currently. I have never been on the Wish. Thus, for purposes of comparison, I am using Fantasy/Dream for DCL and Oasis-class for RC.
Activities: RC wins without any competition by DCL for teens. RC offers multiple waterslides, multiple pools, dry slides, rock climbing, laser tag, ice skating, zip lines, escape rooms, and two flowriders (except Wonder only has one). None of these activities exist on DCL ships (the RC waterslides are far better than the Aquaduck). I would give DCL the edge for the under 10 group. The pool area is better on RCL, but DCL offers characters and more kid-focused events. For adults, its a wash. I prefer RC, but I am not a mega-Disney fan.
Clubs: RC caters to teens, and this includes the teen spaces and activities. My teens far preferred the activities and spaces to the DCL spaces and activities. For the 10 and under set, DCL wins.
Shows: Here, one can argue either way. My teens far preferred the RC shows as they are more adult. Don't mistake me . . . they enjoyed the DCL shows as well, but one can only hear the same songs so many times. And, at some point, real Broadway shows (CATS, Mama Mia, Hair Spray, Grease) are more fun than Disney songs and dancing. Also RC offers awesome ice and aqua shows, and DCL just does not have these venues. DCL offers great movie alternatives (outside and in theaters). For the under 10 set, DCL wins this category.
Pools: RC wins in all categories. The kids waterplay areas on RC are better than DCL, and there is more pool space for teens and adults.
Adult Spaces: Kind of a wash. Both cruise lines offer great adult spaces. RC offers drink packages; DCL does not. This may matter to some, but not to me (I do not drink).
Private Islands: In order of fun (this should not be controversial): (1) Coco Cay (RCL) by a significant margin; (2)
Castaway Cay; (3) Labadee. Of note . . . one can actually get a cabana on both Coco Cay and Labadee. Coco Cay offers the following "no charge" alternatives: great kids waterslides and splash areas (the teen waterpark is a charge, but not the littler kid areas); a giant pool with pop fountains, several beautiful beaches, food, etc. For additional money, you get a water park and/or a beach club with an upgraded restaurant and heated pool.
Food: Here things get controversial. I seldom eat in the main dining room on RCL so I cannot really compare the experiences. I do not love the food in the DCL main dining and far prefer Palo or Remy. And, I am not really a buffet person. For me, there are more options on RCL and the suite restaurant on RCL is great. For the price of an OV cabin on DCL, you can usually get a suite on RCL and the suite restaurant gives a big advantage to RCL. Also, kids can go to the specialty restaurants on RCL, but not on DCL. Thus, food is really hard to compare; the experiences are just different. Obviously, DCL has dinner shows that RCL does not.
Stateroom: Hard to compare here because DCL is so much more expensive. In general, I can get a junior suite (or even a grand suite) on RCL for the price of a Balcony room on DCL. The DCL balcony rooms are more roomy than the RCL balcony rooms. But, I would prefer an RCL junior suite or grand suite to a DCL balcony. On RCL, the suite comes with its own lounge that is far nicer than the DCL suite lounge. More importantly, RCL has a great restaurant for suite guests. But a suite on DCL is so expensive that you just cannot compare it to anything on RCL really.
I have done Star class on RCL (which is amazing). It runs about the same price as suite on DCL. I will not make this comparison as it is not of much interest to most (I think).