If you need some peace to start the cruise, head to sit down. There will always be more people moving around in a buffet.
I have only gone to full service a few times. I like to be able to get up and leave when I want. And can go back and get more or something different. (I don’t think the buffet has great food, and I have basically gotten the same things year after year). A variety for the different tastes in our group leads us to the buffet, too.
I also enjoy the unlimited shrimp and crab claws - serve yourself - no judgment - and no food waste from being served bunches if you only want a few. Ask the server for melted butter if you enjoy it with the crab.
If you have first/early dinner - it comes up pretty quickly after lunch, so take that into consideration. “It‘s dinner time already?” is said almost daily by stuffed people who have eaten breakfast, lunch and poolside snacks when 5:30 comes.
Restaurant menus are also posted outside each restaurant - the MDR off the atrium often has theirs by the side door (entrance without steps, off the Promenade). The other two venues have them by their front door. They post each meal’s menu at the end of the previous one, I believe.
I have not done quick service for lunch. And typically just utilize it for French Fries or late night pizza while watching a movie under the stars. On the Wish, I expect to enjoy the Mexican stand, based on reports from my family. I was excited about the BBQ, but they report that it is “a product of people who don’t live where BBQ is eaten.” My sister describes the brisket as being seasoned like corned beef.
If you want the shrimp, you can go to the buffet and just have them, in addition to a sit-down meal. They don’t limit you to just one place.