Of the mass market lines I believe RCI has the worst food overall.
Just the past couple of years I've become a big fan on NCL. And have cruised them 4 times in the past two years.
The real key to enjoying all NCL has to offer is
1. cruising on the ships which were specifically built for Freestyle cruising (so that's all their newer ships.. Jewel, Jade, Gem, Pearl.
2. budgeting for an extra $100 PP (if its a 7 day cruise), so you can try all the restaurants, which make NCL different from the other cruise lines.