Stir together 1/4 cup sugar, pecans, and cinnamon; sprinkle half of mixture in a well-greased 12-cup Bundt pan. Set remaining mixture aside.
Beat butter at medium speed with an electric mixer until creamy; gradually add remaining 1 cup sugar, beating 5 to 7 minutes. Add eggs, 1 at a time, beating just until yellow disappears. Add banana, sour cream, and vanilla, beating at low speed just until blended.
Combine flour and next 3 ingredients; fold into butter mixture. Pour half of batter into prepared pan; sprinkle with remaining pecan mixture. Top with remaining batter.
Bake at 350° for 45 minutes or until a long wooden pick inserted in center comes out clean. Cool in pan on a wire rack 10 minutes; remove from pan, and cool on wire rack.