I've traveled mostly Carnival with one trip on RCL, and I'm returning to Carnival this summer. There was absolutely nothing wrong with RCL; I felt everything was pretty comparable except (and I would imagine if you have kids this is a BIG except) the room size.
I had always assumed Carnival's bragging about the biggest cabins in the fleet to be, well, bragging. It isn't. My friend and I on the RCL booked a slightly more expensive ocean view cabin and it was significantly smaller than anything I've ever had on Carnival (including my one time in an inside stateroom). My sister and her husband booked the cheapest ocean view cabin...and I swear the room was sized to the bed, with a one foot border of floor space!
No matter what, I am sure you will have a blast!