When we cruise and ask people about their experiences, we hear more complaints about Norwegian cruises than any other. Of course, when we ask we are on a ship other than Norwegian....but you do tend to see a pattern about complaints on food, etc.
you hit the nail on the head, you were on other lines at the time. As a frequent cruiser and a TA let me say, every line is as good or bad as the particular ship. As of now, NCL has the youngest fleet at sea with all their ships less than 10 years old. There were problems with NCLA but actually that is only under the NCL unbrella and not truely NCL. Lately even they have gotten great reviews.
How many NCL ships have you sailed, which ones and when? Hearsay is one of the most dangerous forms news and views.
Now to answer the OP:
Carnival offers larger cabins, which is certainly a plus when traveling with families:
Freestyle offers the chance to eat when you want and gives you flexibility. In fact with freestyle the kids can eat at one time, mom and dad at another. The kids love this.
Both lines offer great kids programs.
We have found the service on NCL a little better than Carnival but probably the food in the main dining rooms is a little better on Carnival. Again, in either case the difference is pretty slight.
Overall you will find mass marketed lines are more alike than different. I have not sailed the Valor but I have the Jewel.
I think you will be happy with either, but if you haven't cruised during the Chritstmas season before you might be in for a shock. Regardless of what line you choose the ship will be over run with families and the service will suffer some. This is not meant to scare you but to let you know what to expect.
Good luck
Nita