As a fan of Palo, both brunch and dinner, both on the Wonder and the Magic, and a veteran of a dozen
DCL cruises, I will weigh in.
The food at Palo, whether brunch or dinner, is significantly better than any of the main dining rooms. Whether you appear for brunch or dinner (or both!) is personal preference, but to the extent your cruise offers both opportunities, do not pass up either.
The food in the main dining rooms is what I would categorize as high-end banquet or wedding reception fare. That is not a criticism; it is simply impossible to prepare gourmet, fine dining for three main dining rooms, and hundreds, if not thousands, of guests at the same time in two separate shifts, given the time constraints and volume of guests. That isn't to take anything away from the experience of the main dining rooms, the food is typically good to very good and the evening festive.
But my sense is that those who prefer eating in the main dining rooms to Palo for dinner say so because they have likely "bonded" with their attentive wait staff, there is a buzz about the room, a theme to the rotational dining and almost a sense of "guilt" when you miss a night or rotation, whether it's one less night seeing your waiters or one less night eating and enjoying the ship with your children. But the food quality and preparation, ambience and service associated with Palo dinner cannot be matched. For me, a foodie, Palo dinner is one of the nicest and best dining experiences, land or sea and simply shouldn't be missed by anyone who likes fine or gourmet dining. Perhaps that "gourmet" experience isn't for everyone, but it is well worth the $15 surcharge as Palo is "all you can eat" and more.
Palo brunch is also an amazing experience. You are in a very nice cold and hot buffet area, you have an entree ordered for you and you can simply "graze" to excellent brunch and lunch options, some of which are quite unique and cannot be duplicated anywhere else on the ship. It is a nice way to break up your early morning or midday, a chance to have something unique and to be somewhere quiet and special. Brunch, too, is outstanding.
If I were to choose, it would be difficult, as both are great experiences. Dinner, however, affords you a greater opportunity to try full entrees that are typically more unique than "brunch fare" and, if you like wine, an opportunity to marry that entree with a fine vintage. If you twist my arm, I would say to experience dinner, but it's an extremely close call and both are not-to-be missed. Enjoy!!