Both! Parrot Cay and Topsiders (BBB) each have buffets for breakfast and lunch. Tritons (Lumieres) has sit down breakfast and lunch. Just depends what you are in the mood for.
My favorite was Parrot Cay (the servers bring you drinks) for breakfast but the men in my family prefered Topsiders/BBB. We did have a couple of sit down meals in Triton's. Breakfast was very good. Lunch was OK but took more time than we wanted...kept to the other choices for lunch after that.
Hope this helps,
Teresa