Which element is more electronegative, sulfur or nitrogen?

Nitrogen is more electronegative.

Nitrogen has an electronegativity value of 3.04 and sulfur has a value of 2.58.

If you don't know these values, you can also figure it out by looking at a periodic table. Fluorine (F) is the most electronegative element, and the closer the element is to it, the more electronegative it will be.