Having been on all the cruise lines, we personally love the food on Celebrity more than the others. Of course, food is very subjective; what one person loves, another will hate.
But we were just talking about this yesterday. Nancy and I spent 17 nights on the Oceania Nautica (which they tout as luxury class but really isn't). In 17 nights there were probably 3 or 4 nights when there was nothing on the menu that got my attention. Whereas on our Celebrity Eclipse cruise, we found the menu to always have things that were of interest. (Personally, we felt the food on Celebrity was equal to or often better than Oceania.) And, as Mike stated, there are the usual menu items that are available every night, such as steak. Plus, the specialty restaurants were awesome! Qsine was amazing and the food was wonderful - definitely something worth trying.
After trying Carnival and Royal Caribbean, I think you'll really enjoy the better quality food Celebrity has to offer. Just my opinion, but we've never been disappointed with Celebrity.