I'm going to play a little devil's advocate here in that I think finding the right cruise line for you and your family is something only YOU can determine, by just booking a sailing and giving it a try. And then maybe cruising again on a different class of ship or itinerary! Everyone vacations so differently, you can get all the opinions in the world and still love/dislike it once you're actually there.
We've sailed
DCL twice (Caribbean & British Isles) and to be completely 100% honest, DCL is not worth the extra cost to DH & I in terms of what we look for in a cruise vacation. We don't have kids so we probably aren't the target demographic either. DH & I enjoy a beverage package, DH likes a casino (which I could take or leave), and we like late night & adult entertainment. For example, on the sea days on our BI sailings, it was the first time we ever got a little bored and a "well what do we do next?" mentality. The only indoor activities seemed to be bingo and trivia and the hottubs were never not packed full. There were other little things as well that I didn't love, such as no buffet for dinner, but nothing major.
On the other hand, the ships were beautiful, we loved the idea of rotational dining, the cabins were adorable, and the theater shows were fantastic. But in terms of overall value, that doesn't justify the overall cost FOR US. We LOVE DISNEY, but have learned to get our fix in the parks!
We do enjoy Carnival quite a bit and are very excited to try out the new ships and we have an Alaskan sailing booked on NCL in 2021 (fingers crossed!), which will be a first for us. I'd like to try Royal in the future as well. I think the best thing you can do is just book a cruise on the line you want to try and go for it!