We have had a lot of great cruises on Celebrity and Holland America.
We tried NCL and both times the food was really really bad and recycled day to day because no one ate it. They were always out of cups, plates, silverware in the buffet, empty towel bins at the pool every time you checked--room steward missed more than half the times, used plates, cups, and food rolling around the pool deck, really bad.
We call it the Neveragain Cruise Line because so many reviews on cruisecritic are titled Neveragain on NCL or worst cruise ever.
NCL is like staying offsite at a Motel 6 where Celebrity, Holland, and Royal have the great service, cleanliness, and friendly staff you find onsite at Disney. Ironically prices are often very close.
Our kids have enjoyed the youth programs on HAL and Celebrity. Sadly the youth workers on our NCL cruises did not show up many times throughout the week. We joked that Freestyle must include an option of going to work or not as adult activities had many crew no shows as well as our room steward.
I will say that formal nights and dressing for dinner are expected on both lines I reccommend. The freindly crews with great service and food are worth it.