The group I traveled with to Merida was made up entirely by a crack team of chefs and restaurant managers. Nectar was the consensus favorite for dinner during our 4 days in town.
In particular, the shocking (in a good way!) blackened onions that are indistinguishable from coal until you take a bite, and the beef shortrib in recado negro were favorites.
Personally, I fell hard for the roasted chicken, rich in a sauce made of jus, but with nuanced acidity coming from perfectly prepared vegetables. Nectar is a great restaurant!