Princes has Personal choice dining & traditional dining.
NCL has Freestyle but I am not sure of any other mass market lines where you can go to the dining room anytime most have the traditional (set time) dining.
Food is subjective so that is something only you can decide on .
Go to Cruise Critic and read the reviews on the lines you are interested in.
We sailed both lines (not the Jewel) but found Princess was better for us.
Alexandr Pushkin, Carnival-Holiday, HAL-(old)Westerdam, Orient lines-Marco Polo, Royal Olympic-Olympic, NCL-Dream, Dawn-Princess, ACCL-Grande Caribe, Oceania-Insignia (3), Regatta(4) Marina (1) St Lawrence Cruise Lines-Canadian Empress
Scenic River cruise June 11,2012