Preheat the oven to 325 degrees F (165 degrees C). Lightly grease and flour two 8x4-inch loaf pans.
Beat together sugar and butter in a large bowl with an electric mixer until light and fluffy. Beat in eggs one at a time, mixing well after each addition. Stir in banana and sour cream.
Combine flour, pecans, baking soda, baking powder, and cinnamon in a separate bowl; add to banana mixture, mixing until just combined. Pour batter into the prepared loaf pans.
Bake in the preheated oven until a toothpick inserted into the center of each loaf comes out clean, 55 to 65 minutes. Remove loaves from the pans and place on a wire rack to cool. Serve warm or cold.