I only have experience with
DCL here, but can say that what pushed us over the edge to pay more for DCL was talking to a friend who cruised with NCL (on the Encore I think). She was really let down by length of time in ports, always having to walk through a smoky casino to get anywhere, and very few offerings that were truly kid friendly. I found a YouTube channel called Window Seat and thought the DCL Alsaka cruise video was really well done. He took his family and you really got a good feel for what it is really like. We had a very similar experience to his.