Preheat oven to 400°F. Prepare 18 muffin cups with liners or lightly spray with non-stick cooking spray.
In a medium-sized bowl, whisk sugar, buttermilk, yogurt, oil, egg and vanilla until combined. In a larger bowl, whisk together flours, baking powder, baking soda, salt, and chocolate chips.
Add the wet ingredient mixture to the dry ingredients and mix just until combined. Do not overmix.
Fill the muffin tins about 2/3 to 3/4 of the way full. Bake for 15-18 minutes or until golden brown. Cool slightly before removing muffins from muffin tin and cooling completely on a wire rack.