I only cruise with Disney. It costs double, and it’s worth it.
We usually cruise on Princess (surprisingly, owned by Carnival!), and really like it. We tried Celebrity last year and will never do that again. Disney looks interesting, but it seems that it would have too many kids. Also, we’d rather not give money to Disney. (Are there a lot of “alternate lifestyle” passengers?)
Our neighbors who are in their 80s only go with Disney.